Wednesday 3rd January 2007
First meeting of the Year
As this was the first meeting back after the Christmas break, an informal coffee and chat evening was held.
After a day of gales and heavy rain, wonder of wonders, the sky was actually clear and Moonless on an observing evening. Lots of scopes turned up and we looked at the sky. Fantastic!
It clouded over again by about 2130, but stayed clear long enough to remind us what the night sky looks like.
Wednesday 17th January 2007
Ed Goward - Refractors
This evening, Ed took us through this kind of telescope. First he explained that they worked by splitting light through a lens to provide the magnification. The eye works in a similar way so the oldest refractors are to be found in trilobite fossils from millions of years ago.
A single lens has the problem that when the light is split, it spreads out into different wavelengths or colours, which have different focal lengths. This means that images have colour fringes. This can be corrected by adding additional lenses.
He demonstrated his refractor which was mounted on an equatorial mount so it can track objects in the sky manually. He said it was ideal for wide field views. He explained that different telescopes have different uses and whilst this was the best one for this type, higher power viewing was also possible.
I then demonstrated his Meade ETX-70 which is also a wide field refractor, but is computer controlled. I also told the tale of how two pieces of lens shaped glass, found in a Viking tomb from a thousand years ago, but made many centuries before in Babylon, turned out to be a simple refractor when mounted correctly in a tube with a distance between them that they were found in the ground. The original tube had rotted away leaving just the lenses.
Ed rounded up by taking about different types of refractor. All in al a very interesting evening.
Wednesday 24th January 2007
Whilst it was touch and go to start with, we had another clear evening for observing and several scopes were set up to observe domes on the crescent Moon, Saturn, M42, M45 and various other objects. There was a little bit of cloud, but it stayed clear for most of the time. It was however, very cold.
Wednesday 31st January 2007
Mike Culley - Rockets
Mike did a talk on rockets tonight. He started off in ancient times with the Chinese who invented gun powder and used the rockets for fireworks and as weapons of war against invading Mongols. The Mongols made their own and also passed the technology to India an on into Europe. The Indians used rockets against the British during the 18th Century. The British developed them in the 19th Century for warfare and used them against the Americans, the French and the Danes. The US national anthem, "The Star Spangled Banner" has a line "The rockets red glare" which refers to this.
In the latter part of the 19th Century they passed the technology on to the American who used it against the Mexicans.
Fins were used to add stability and the range could be several miles.
Despite all this, it never occurred to anybody to use them send things into space. Jules Verne used a cannon to launch space craft, as did HG Wells for his Martians.
A Russian finally said they could be used for space. He also proposed multi stage rockets and liquid, rather than solid fuel, which had been used up to then.
After WW1, the German's were banned from munitions development, but not from rockets, so thy developed them as hobby and scientific objects. Hitler turned this into weapon research and Werner Van Braun developed the V2 during WW2 to send explosive warheads to England.
After WW2 he went to the US and started work on the ICBM and space programme. The USSR also got some rocket experts and started their own programme. They were the first to get a satellite, Sputnik, into orbit. It was more of a statement than anything else, but it woke the US up who launched their own satellite Echo 1 shortly afterwards. The Russians then put a dog into space and then a man. The space race then started.
Terry - Apollo 11 to the Moon
Terry did an evening on this landmark mission. He went through the history of Moon flight development. He explained how the US set up Cape Canaveral. I went through some details of the base.
Then using clips he showed the whole of the mission itself from start to finish. This included the launch, the journey, the landing, the Moon walk and the return.
Mike went through Lunar geology very briefly.
All in all a very good evening.
Wednesday 14th February 2007
After a day of of heavy rain, the front cleared and as predicted by the BBC's cloud forecast, at 1830, the skies cleared and were very transparent. Even the light pollution from Southend was virtually non existent. This combined with no Moon, made an excellent observing night. in fact I think it is one of the best skies have I seen form the Church. Lots of scopes and a good time was had by all.
Wednesday 21st February 2007
All - Science, Space and Science Fiction
Mike gave a quick briefing on Saturdays Open Night. We then moved onto the main part of the evening.
We had decided to try something different this evening. Members were invited to come along and speak about a favourite science fiction programme. We wanted to know what they liked about it and also how accurate any depictions of science were. They were invited to bring along clips and pictures to illustrate their points.
Mike started off with a BBC programme from 1973 called "Moonbase 3". This was set in the early 21st Century and they tried to make it as realistic as possible. There were no aliens, just various factions, British, American and others, each with a base on the Moon. The sets were wobbly, the acting wooden, and the base appeared to have full Earth gravity inside. Still it was quite ground breaking for its day.
Bruce then talked about the 1950s Gerry Anderson animation show, "Fireball XL5" This has a cast of puppet characters including Steve Zodiac, his girlfriend Venus, Professor Mat Matic and a robot called Robbie. "Fireball XL5" was a pace craft dispatched to various planets from a place called Space City to have adventures.
Wherever it went though, there was always a launching ramp for it. He said that the spacecraft could split into two, the smaller bit called Fireball Junior. The characters chewed Oxygum which meant they could breathe in space. This was done as the puppets' strings prevented them from wearing space helmets. In one of the adventures they went back in time to the Wild West
I added that this was probably Anderson reusing the sets from his earlier cowboy puppet show called Four Feather Falls. He was fond of reusing sets in different shows. Andrew also said that eh set his shows in the future so that travelators and hover scooters meant that his puppets did not have to walk.
Janet then talked about "Dr Who". It first appeared on BBC TV in November 1963 with a story called The Unearthly Child. The Doctor is a time traveller who goes through time and space in his ship known as the TARDIS. This is disguised as a police box and is much bigger on the inside than it is on the outside. Janet showed a clip from the story which was voted the best of all time by fans.
It was called "Genesis of the Daleks" and featured the forth incarnation of the Doctor, played by Tom Baker. The clip we saw was the start of the story the the Doctor is sent to the planet Skaro to a time just before the Daleks appear. There is a war going on between the two races on the planet, the Kaleds and the Thals. The Kaleds are mutating due to all the radiation on the planet and Davros, a mad scientist is turning them into Daleks. The Timelords have sent the Doctor there to prevent the Daleks appearing as they predict they will take over the universe.
Mike added that during the time of Tom Baker playing the Doctor, many members of CPAC, himself included , wore long scarves with pockets in them.
Mike then talked about Gerry Anderson's first live action show which was called "UFO". Made in 1973, it was set in 1980. It was about SHADO (Supreme Headquarters Alien Defence Organisation) who were tasked with protecting the Earth again attacks by aliens in UFOs whose planet was dying so they were coming to Earth to steal human bodies.
SHADO was based under the Harrington Straker Film studios. They had an unmanned space station called SID (Space Intruder Detector), a Moon Base where interceptors would be launched against incoming UFOs, a submarine called Skydiver which could launch an aircraft from underwater called Sky One, and lots of ground attack vehicles. He showed the opening sequence of the show which showed all of these. Skydiver was interesting as it was only ever shown form one side. This was because it had Sky written on the aircraft bit and Diver on the submarine. This would not have worked on the other side.
It was darker and more adult than earlier Anderson shows and had racist comments and on screen smoking which would not be acceptable now. It also had adult relationships, drugs and violence. Some of the characters changed halfway though as despite it only being one series, filming was interrupted by a strike.
In one episode, a woman shoots an alien breaking into her house, thinking it was her husband who she plane dto kill so she could run off with her lover. She hoped to convince people that she had mistaken him for an intruder. this left SHADO with a dilemma. Secrecy was paramount so whenever a member of the public encountered a UFO or an alien, they would give them an amnesia drug afterwards. If they did that to this woman though she would forget the incident and try to kill her husband the next time he came in.
In another episode George Cole stars as a man whose wife has been killed by the aliens and e is sent out on to the Moon with a bazooka to shoot down an alien craft as it approaches. this proves it did attract some quite famous faces.
I added that the female staff on the Moon base wore purple wigs because Gerry Anderson's wife Sylvia, who designed all the costumes, liked wigs, which were fashionable in the 1970s, and assumed that one day they would be part of uniforms. He said that the show had a gull wing car, (on which the doors had to be held open because they did not really work) and car phones. It also had vehicles in Britain driving on the right as Anderson assumed that by 1980, Britain would have changed over.
Kevin added that he had seen Colonel Straker's (the leader of SHADO) car when it had been in a garage near where his dad worked for valeting. It did not actually work, but had to be towed.
Mike then discussed the BBC series "Red Dwarf". Set on a mining ship of the same name it was about a man called Lister who was sentenced to suspended animation after being convicted of insubordination on the ship. The ship then suffered a radiation leak which killed all the crew. Lister survived this and was released from suspended animation 3 million years later. All the crews remains have turned to dust and he is apparently the last human in the universe.
His only companions are Rimmer who is a hologram of his former cabin mate, Cat, a descendant of the ship's cat who have evolved into a humanoid life form and the Ship's computer Holly, played as both male and female personalities. They are later joined by Kryton, a housekeeping android.
Mike showed a clip where they were discussing how attractive the female characters in "The Flintstones" were. The show combined wacky humour with very advanced sci fi concepts such as time travel, alternate universes, including one where time runs backwards, which Mike showed, and various creatures and gadgets. All of the characters came from Earth though. There were no aliens in it though.
Andy then discussed the "Wallace and Grommet" film, "A Grand Day Out", from Ardman Productions. He said he did not watch films or TV much, but liked cartoons and found this one very funny. They are the claymation characters made of clay which are moved and shot frame by frame. Wallace is an amateur inventor who is voiced by the actor Peter Sallis, who also plays Clegg in "Last of the Summer Wine". Andy said the two characters were interchangeable. Grommet is his faithful and very intelligent dog.
They decide they need to go out of the day on a Bank Holiday. Wallace is looking at a brochure of cheese holidays. They both then look at the crescent Moon through the window. Wallace says "Everyone knows the Moon is made of cheese."
Andy describes how they go to the Moon. When they get there, they get out with out any space suits with all their picnic gear and look for a nice picnic spot. They come across a weird coin operated space cooker which then pursued them with designs of going to Earth to ski. The only nod to real space is he throws a ball in the air and it does not come down.
He showed a clip of Wallace going down to the cellar and designing and building a space rocket. He is on a door which he is sawing held up by two trestles, one of which he saws through. He ten uses Grommet as a trestle. He builds the ship and they both get inside. It is decorated with wallpaper, sideboards, pictures etc. Wallace goes out and lights the fuse. He then realises he has forgotten the crackers for the cheese and gets some form the kitchen in the nick of time,. The rocket lifts off and as it does so, all the rats in the cellar put on sunglasses. Andy said he firmly believed "A Grand Day Out" to be science fact and will be looked back on in a couple of hundred years as past of the development of rocketry in the late twentieth century.
Mike then moved the evening across the Atlantic to discuss Gene Roddenberry's "Star Trek". He showed a clip of Captain Kirk and co materialising on a planet and asked what was the first thing to note. I replied that the actors in red who you had never seen before and would never see again, would shortly be killed. Mike said they were there to show how the monster worked. Mike added that Captain Kirk always had trouble keeping his shirt on and like to pose.
Despite the clichés, the show was groundbreaking. It was set in a future where there were no prejudices and different races such as Russians and Americans, got on. It had a black female in a strong leading role (Lieutenant Uhuru). When the across who played her wanted to leave, Martin Luther King asked her to say on because she was such a role model and she agreed.
"Star Trek" spawned many spin offs, one of which "Deep Space Nine" which was talked about by Ed. it was set on a captured space station on the edge of the galaxy, near to a stable worm hole to another part oft he galaxy. He showed the opening sequence of the show.
It had lots of interesting characters including Quark, an alien barman who had holosuites where you could enjoy entertainments not suited to a family audience (and of course, only inferred), and Odo, a shape shifter. He showed a sequence of Odo eavesdropping on criminals whilst disguised as a rat. Odo did not know where he came form or if there were any others like him. Every sixteen hours he had to rest by pouring himself into a bucket.
Ed then revealed that he too was a shape shifter, and every sixteen hours eh had to rest in a bucket. He produced a bucket and said he would pour himself into it, but needed absolute quiet and no sniggering from the audience. After building up the tension, he put the bucket on his head to reveal it had a smiling face on it. Follow that!
David had to by talking about a series called "Firefly". only fourteen were made, but film called "Serenity" was a follow up. It was set in a system of planets where lots of Earth colonies were established. Some were quite advanced, others were very primitive and wild west like. Dave described it as the bits of the Galaxy that the Enterprise would go straight past. Firefly was a tramp space ship which was poorly defended and had a roguish captain and crew. He showed a clip there they were defending themselves against being sucked into a space ship dismantler by using a handheld weapon. he said the good thin about "Firefly" was they had space as being completely silent.
I finished the evening by saving what I thought was the best until last - "Babylon 5".I let the show introduce itself by showing a clip of the opening sequence of the second series. I felt that it was the best TV sci fi show ever made. It was unique in as much as it was one continuous story, almost like a novel, with a plot which was comparable to "Lord of the Rings" in length and complexity. It could be very intense to watch and you dare not miss a minute. In some episodes something could happen in the background which did not have significance until several episodes later. "Deep Space Nine" had tried something similar, but not as well.
It was set on the last of the Babylon Stations in the mid twenty third century. The place was a kind of United Nations in space were humans and aliens could meet in peace for trade and diplomacy. Dark forces were at work in the background however and two ancient races were pitting the younger ones against each other in war to see who survived. At first it was thought one was good and one evil, but nothing was so clear cut in "Babylon 5".
It acknowledged that there was no gravity in space. In "Star Trek", everything in the ship could fail, but the crew always remained firmly stuck to the floor. Only in one of the films did the gravity briefly fail. In one "Second Generation" episode of "Star Trek", Captain Picard and some children are trapped at the bottom of a very deep shaft on the Enterprise after a ship wide disaster and they have to climb up it. I asked, why not just turn the gravity off?
In "Babylon 5" the station and space ships are spun to simulate gravity and some areas are in zero gravity. Some of the alien ships do have artificial gravity which they later give the humans. it also acknowledged that in space there is no up or down. In other space shows the space craft are always aligned the same way and small ships launch off big ones like an aircraft carrier. Ships launching from Babylon 5, just rotate through ninety degrees and fly away.
It solved the problem of faster than light travel by having jump gates, an idea borrowed from "Buck Rogers in the twenty fifth century". These allowed passage into hyperspace and the out again though another gate in another star system. bug ships carried jump point generators to make their own gate ways. This technology had been given to humans by initially friendly aliens. You could get los tin hyperspace and never emerge and there were dangerous creatures lurking in there.
"Babylon 5" had lots of shades of grey and did not have caricatures like all of one race are evil or good. I showed a second clip which summarised the story, but we were out of time so I had to stop.
All in all a very different, but enjoyable, evening.
Saturday 24th February 2007
Open Night - Hadleigh Country park
Club Members turned up at 5pm to set up for a 6pm start. It did not look promising as it was overcast and trying to rain. We could not get onto the field so we assembled in the car park. We waited until nearly 6pm and members of the public started to turn up. Holes appeared in the cloud and Venus and the Moon were sighted so telescopes were quickly set up.
In the end we had a whole range of telescopes set up, mostly on the Mon which kept making guest appearance through the Clouds. We had a camera scope attached to the projector showing the Moon on a big screen. We also had another scope attached to a web cam which allowed visitors to capture their own images and have it e-mailed it them.
In total we had over 150 visitors and despite the weather, it was a very successful evening
Wednesday 28th February 2007
As it was cloudy and blowing a gale, tonight was a beginners' evening. Mike started off by showing some pictures of the open night and detailing how it went. He talked about the occultation of Saturn by the Moon, due in the early hours of March 2nd and the total eclipse of the Moon, due on the evening of March 3rd.
Ron then showed the members the two new solar scopes that he purchased at Astrofest for the Club. One is a Hydrogen Alpha scope and the other is a Calcium K scope. The Club had also purchased a laser collimator, a diffraction grating and a book on double stars.
During the break there was a caption completion based on a picture of Andy standing by an enormous Meade Scope at Astrofest. Yours truly one it with "How many pen cells does it take??"
After the break, Janet gave a short talk on astronomer Jocelyn Bell Burnell, the discover of pulsars. Janet briefly described her career and achievements. She had actually found the pulsars as a research student on a project looking for quasars. On the recording traces from the radio telescope, she found some signals which she called scruff. These appeared to be regular radio pulses set 1.3 seconds apart. After terrestrial sources for the signals were discounted, it was wondered if they were signals from aliens. Someone even wrote LGM for Little Green Men, on the trace and this stuck for a while. They then found another source, in a different part of the sky pulsing at 1.2 second intervals and then many others,. Since it was unlikely that different aliens would be transmitting the same kind of signals from different stars, there must be a natural explanation.
It was found to be pulsars. These are caused by rotating neutron stars which are the very dense, collapsed remnants of supernovae. As these rotate, they emit a beam of radio waves, just like a light house, so they appear to wink or pulse at us. The most famous is in the Crab Nebula in Taurus, which was observed to explode in 1054 by the Chinese and was visible in daylight.
Mike rounded the evening off by describing how to find the Crab Nebula.
All - Winter Picture Roundup
This evening posed a bit of a dilemma as it was clear, moonless, but not an observing night. A few hardy souls, myself included, brought our scopes and spent the first hour observing. The rest of the Club, not expecting an observing night, stayed inside to look at the various pictures that Club Members had taken over the Winter.
I came inside at 2100 to catch the second half of this evening. The Lunar Eclipse of 3rd March was prominent, as was the Occultation of Saturn by the Moon on 2nd March. There were the usual deep sky wow shots from the usual suspects, plus I showed my web cam image of Saturn taken through the ETX-70. Small, but perfectly formed!
Wednesday 14th March 2007
As it was cloudy, we had a beginners' night. I started off with some news about the STEREO mission. This is two satellites orbiting the Sun in the same orbit as Earth, but one will be a million miles ahead and one will be a million miles behind. This is so it can take three dimensional images of the Sun. At the moment they are on the way there. To calibrate the cameras they needed a black shot. To do this they took pictures of the Moon transiting the Sun. As they are further away from the Sun than the Earth, the Moon is much smaller so does not cover the whole disk of the Sun as it does during an eclipse from Earth. I showed the movie of the transit.
I then described the new Orbital Express mission. It was launched on 8/3/07 from Cape Canaveral on an Atlas V rocket. Its mission is to demonstrate on-orbit refuelling, component exchange and satellite repair All without a human operator In a nutshell, ASTRO will dock with NextSat and service it Mission has two parts: The Autonomous Space Transport Robotic Operations (ASTRO) service vehicle and the Next-generation serviceable satellite (NextSat).
Who will pilot ASTRO? The answer is not who but what the Advanced Video Guidance Sensor (AVGS) Mounted on ASTRO, AVGS shoots infrared laser beams, which bounce off a pattern of retroreflectors on NextSat. By analyzing reflections, ASTRO adjusts its speed and angle of approach to safely close the distance and make contact.
Eight test series will be conducted during three-month mission. ASTRO and NextSat will conduct approach and docking manoeuvres from starting points up to 4.3 miles (6.9km) away Once docked, they'll also swap propellants and trade and install batteries - first unassisted component exchange in space history Tests will be conducted at different times of day to see if darkness on Earth's night side confuses the imaging system.
George then described his interest in astrophotography. He started by taking pictures of Hale-Bopp. He then got a digital SLR and took pictures of Orion, the Transit of Venus, other star clusters and the recent Lunar Eclipse. He uses his ETX-70, either a-focal or through an eyepiece adaptor. He also bought a small equatorial mount and adapted the ETX-70 tripod to mount it own. George proved that you do not need lots of kit to get decent pictures.
Mike rounded off the evening by going through all the objects that can be seen in the spring sky including various star clusters and double stars.
Wednesday 21st March 2007
Andrew Mowbray - Radio Waves
Mike started the evening with a reminder about the open night on Saturday.
I then started the main talk for the evening. I described how he had always had lots of interests, but two main ones, amateur radio and amateur astronomy. I described how I had got into the hobbies, the differences and how they had many similarities.
I then described how radio communication is used and regulated. All radio transmitters need licences and have to be approved for use. Amateur operators are also licensed, but can build their own equipment.
I then described what radio waves were and the physics governing them. Normally they are line of sight, but under certain circumstances instead of going out into space, they get reflected back to Earth. This is related to the activity of the Sun which ionises the atmosphere and causing a layer in it called the ionosphere which refracts radio waves back to earth. It also has different effects on different frequencies.
I described how the different radiations and particles that the Sun emits causes different effects in the ionosphere. splitting into layers and how these affect radio waves over daily, seasonal, yearly and the Sun eleven year cycle of sunspots.
VHF frequencies can also be affected by changing densities in the troposphere.
Wednesday 28th March 2007
Tonight started with a visit from a photographer from the local paper. Various club members posed by telescopes and I had to hold her while she stood on the fence to get some pictures. (Don't ask!) We then went inside where she took some more pictures. After that, Terry did a presentation on recent solar activity followed by a video from the "Sky at night" about the sun.
Nik Szymanek - Pixel Magic- Introduction to Image Processing
Tonight saw a welcome return to the Club by Nik who went through basic techniques on how to use software such as Photoshop to make initially unpromising looking astrophotographs look very good. He demonstrated on pictures of comets, galaxies and clusters. It was a very interesting and inspiring evenings.
Wednesday 11th April 2007
Tonight was clear so we had an observing evening. We started by waiting for the sun set to view comet 2P/Encke. It is below Venus at the moment. We watched for a while, but by the time it wad ark enough to probably see it, it had gone too low so now sighting as yet.
We had lots of scopes set up and once it had got dark enough we viewed Saturn, M13, M44 and other objects of interest. Conditions were a bit misty, but it was not a bad nights observing.
Wednesday 18th April 2007
Spring Picture Roundup - All
Terry opened the evening by showing us a montage of pictures and movies taken on our trip to the dark site at the Dengie on Saturday night. He showed us the site, the sea wall, us observing and also some pictures of Venus, stars and Saturn taken with the camera and through Bruce's telescope.
After the break, Pete, George, Eddie, Brian and others showed us some of the pictures they had taken recently.
Wednesday 25th April 2007
Tonight started with us welcoming back our Chairman Mike from his travels to Australia. I presented him with a copy of the Echo which had the article about CPAC and his picture which was taken before he went away. It was dated on his birthday which was a nice coincidence.
We then continued our "Me and my telescope season" with Bruce then gave us a warts and all talk and demonstration on his Meade LX-90 LNT telescope, an 8" Smitt-Cassegrain. He did some research before buying it and found that most of the dealers were offing very similar prices. This was apart from one in Cornwall, which was much cheaper. He did not want to go all that way, but he noticed another dealer were offering a price match so he went here and made them match it. He took it home and had to wait or clear skies.
When they finally arrived, he found that it would not align to the sky. This was because, when he put in 31"E,it kept converting to 31'E. It was either a problem with the Autostar handset or it was a problem with the LNS (Level North Technology Unit). He contacted the dealer and was told it was a known a problem and he was to return the Autostar which he did. In the meantime, he checked the battery in the LNS and found it was flat. he told the dealer this, but they said that was not the problem. A few days alter the Autostar was returned to him and it turned out that the flat battery was the problem after all!
He then had to wait for the next clear sky to try it again. It worked for a while and then broke down again. He returned it again and it turned out a wire had burnt through inside. They repaired it, upgraded the Autostar and also added the new GPS module to it free of charge. This allows the telescope to work out where it is, the date time and then level itself and do all the setting up.
Bruce said it now works well, is optically very good and he how had a lot of fun using it. To avoid problems, he recommended making sure the locking clamps were tightened before aligning it. Gerald recommended having the cord warp on when using external power supplies. I recommended using Velcro to attach the handset to the scope when it was not being held.
All in all , it was a very entertaining demonstration from Bruce.
After the break, I mentioned about the news that an extra-solar planet, had been found orbiting a star 20 light years away, and this planet was believed to be only one and a half times the Earth and the right distance from its star for the possibility of liquid water existing on it s surface. it could therefore be the most Earth like planet yet discovered.
I then went on tot do a presentation on the New Horizons mission to Pluto. Launched in January last year, at the end of February this year it used Jupiter to get a gravity assist to speed up it slight to Pluto, thus taking five years off the journey.
As it approached Jupiter, its instrumentation was turned on so it could be calibrated against a known target, to do some science, and to get some pretty pictures. It has got some very good pictures of Jupiter itself and also of two of it moons, Io and Ganymede. On Io, it took the best pictures yet of the huge volcanic eruptions that take place there. It got the best pictures yet of the Little Red Spot, a giant storm on Jupiter itself.
It is now flying down the magneto tail of Jupiter. This is the side of it magnetic field which is stretched away from the Sun by the solar wind and reaches halfway to Saturn. It is taking measurements as it goes.
Astronomers' Question Time - All
The evening started with Mike reminding everyone of the exciting series of outside speakers that we have coming up. He also reminded everyone about the open evening on the 19th May at the Country Park. I announced that we were planning to go to the exhibition of Hubble Art in London on 2nd June. Terry reminded everyone that we had been invited to do a stall at the Village Fayre in the summer.
We then moved on to Astronomers' Question Time. I introduced the distinguished panel which consisted of Mike Jim, Dave, Eddie, Pete, Andy and myself as chair.
The first question was about a concern that a new experiment at CERN may create a short-lived black hole which in theory could destroy the Earth. It was discussed at length and decided that the black hole would be extremely short-lived before it evaporated as hawking Radiation. Also cosmic rays hitting the Earth had much higher energy that CERN could produce and these did not seem to create black holes. It was also noted that back holes in space are still a mathematical concept and have not been directly observed, only inferred. It may even be the case that insufficient time in the universe has passed for the singularity, which is the heart of a black hole, to have yet formed. All you would see inside the black hole, if you could see in, would be a wall of dense matter, apparently frozen in time. It was mentioned that a black hole the with the mass of the Earth would be the size of a large marble, but a black hole with the mass of the universe would be the size of the universe. Are we therefore already inside a black hole?
In the next question, the panel were asked if they could be a famous astronomer, alive or dead, who would they be? Answers included Fred Hoyle, Hubble, Galileo, Fred Espernak the eclipse chaser, William Hershel, Carl Sagen and Edmund Haley.
The panel were then asked how energy can be converted to mass and vice versa and there was a brief discussion on relativity.
The panel were then asked why, if Venus was a similar size and composition to the Earth, while it had no plate tectonics. The answer was that unlike Earth, because it way nearer to the Sun, Venus has lost all is oceans of water early as there had been no life to lock most of its CO2 into the rocks, as had happened on Earth. This meant there was no sea water to lubricate the plates where they met collide and where one normally goes underneath the other one, a process known as subduction. On Venus all the plates therefore locked to together and you get massive shield volcano eruptions which cover large areas of the planet with lava. These happen at very infrequent intervals however.
The next question was about Gamma ray bursts. If they are produced by black holes, how does the energy escape if nothing not even electromagnetic radiation can escape from a black hole. Also why is their output directional and why does it last longer than originally expected? Gamma ray bursts are caused by star collapsing into itself to form a black hole. The energy is given of as it spirals inwards so at this point it can still escape. It is directional due to the spinning nature of the collapse projecting the energy along the rotation of spin. It lasts longer than first thought as the initial energy can cause secondary excitation in the surrounding material.
The panel was asked if any planets rotated the opposite way to the Earth? Venus does and Uranus might do depending on definition as it lies virtually on its side in relation to its orbit so it depends which pole is defined as North and South.
It was asked if comets can be seen hitting the Sun. The answer was probably no as the Sun is much brighter and bigger than a comet. All you would see is the comet disappearing.
The panel were asked what Gamma rays were. They were defined as extremely high frequency, short wavelength electromagnetic waves. Not to be confused with cosmic rays, which were actually very high energy, very fast particles.
There was then a discussion as to the differences between GMT, UT and UTC which is was agreed were the same for all practical purposes, whether the whole world should use the same time zone and whether the clocks should go back and forward in the spring and autumn. The result of the debate was inconclusive, but a slight majority were in favour of leaving things as they are.
Wednesday 9th May 2007
Mike started off by organising the Open Evening on 19th May.
Dave then demonstrated his 12" reflector with his new Dobsonian mount. He demonstrated how it worked and let members have a look at it.
Andy then did two astronomical news items. The first was on the new COROT satellite which was designed to find planets around other stars, possibly as small as the Earth and to detect the interior make up of other stars. it had found its first "hot" Jupiter planet, a gas giant very close to its star and was performing much better than it was originally expected to.
The second item was a new technique to observe both supernova explosions and their after effects by observing light reflected off of dust shells at very distances from he supernova which arrives after the light from the explosion itself.
Mike rounded off the evening with a tour of the spring sky.
Wednesday 16th May 2007
X-ray astronomy - Dr Carolin Crawford
Tonight we were fortunate to be visited by Dr Crawford of Cambridge University who gave us a talk on the above subject.
She started by describing what X-Rays are. They are very short wavelength, extremely high frequency electromagnetic waves. They are high energy and require a heat source much hotter than that required by visible light, to be produced. they can also be created by highly charged particles passing through an intense magnetic field.
Naturally occurring X-Rays from space can only be detected by instruments above the Earth's atmosphere as they are absorbed by it. Early observations were done using balloons and rockets. Observations are now done by satellites such as Chandra which are in Earth orbit. To detect the X-Rays, you can just use a reflector mirror as you would with visible light as it would absorb the X-Rays. Instead you have to glance them of a series of mirrors at shallow angles to bend them towards the detector.
Dr Crawford then showed us two images of the sky around Orion, one taken in visible light and one taken in X-Ray. Both were at the same scale. In X-Ray, normal stars are quite faint as they do not give off huge amounts of them. For example the double star Sirius has one of its component stars, Sirius A, which is very bright in visible light, is virtually invisible in X-Ray, where as it small companion, Sirius B, is hard to see in visible light, but is very bright in X-Rays.
T She should a picture of the Sun taken it X-Ray. Its surface is black as it is too cool to produce X-Rays. Only the intense magnetism around solar flares produce them, There is also excited gas in the outer corona that also produces them. Only stars within about a thousand light years can be detected in X-Ray.
Strong X-rays sources are found in supernovae remnants, at the centre of galaxies and in areas where there are believed to be black holes. In fact the are good evidence for black holes and the sources at the centre of galaxies, including our own, may be supermassive black holes. The X-Rays are produced as the matter is absorbed into the black hole.
X-rays are also produced by gas between galaxies, other as a result of them colliding. She showed an animation showing that this will one day be the fate of our on galaxy, the Milky Way, when it collides with the Andromeda galaxy.
She was asked if X-Ray telescopes suffer from chromatic aberration. She said they did, and it was even more pronounced than that suffered by visible light telescopes. She was also asked if the telescopes could take the image all in one go or had to move across the required field of view and buid the image up, as radio telescopes do. She relied that the detector in an X-Ray telescope was a CCD chip which is much more sensitive and has a greater resolution than it optical equivalents. They were therefore able to image in one go and provide a high quality X-ray image which complete spectrum information for each pixel, something visible light CCDs can not yet do.
All in all, an excellent talk an speaker who we look forward to visiting us again.
Saturday 19th May
Despite a rather unpromising start, when it was cloudy, the sky did clear and we had good views of the Moon, Venus and Saturn. About two hundred people attended.
Wednesday 23rd May 2007
I was away for this one, but apparently Andy did some news items including on on Prince Philip and a space toilet. (Don't ask!) Dave then did a piece on star trails.
Wednesday 30th May 2007
Near-Earth Objects and the Impact Hazard - Dr Andrew Ball
Tonight we were fortunate to be visited by Dr Ball of the Open University. He started by showing just how many objects there are in orbits near to the Earth's, many of them actually cross Earth's orbit. He showed the Arizona crater that proves things do hit the Earth and he said traces of may others have been found, but tectonics and erosion tends to mask them or make them vanish all together.
These come n all shapes, sizes and compositions. They range from tiny fragments, to objects many kilometres in size. they can be loose rubble piles or dense iron objects.
Ground based observatories and satellites are constantly discovering new ones. When one is discovered its orbit is plotted and a threat level on the Torino scale is assigned to. This ranges from 0 which is no threat to 0 which is a certain impact causing a global catastrophe. As more readings of the object are taken, its orbit can be refined and its threat level reassessed. There are no current known objects that are due to hit the Earth.
The Earth's atmosphere protects us from smaller objects and even some larger ones, is they have a loose composition would explode in the atmosphere rather than hit the ground. The Tunguska explosion in 1908 is believed to be such an impact. It flattened trees, but left no crater.
If an object was on a collision course with the Earth, it is likely that we would have many years, possibly decades, after it was detected, to take action to divert or destroy it. To divert it, several methods could be used. One would be to fly a mass into it to change its course. The further away it was, the smaller the mass would be need to be a small nudge a long way away is the same as a big shove much closer. Even flying a mass near to it could effect it enough to change its orbit. Care would be needed that it did not then pose a threat on subsequent orbits.
Painting the object black on one side could work as light pressure from the Sun would alter its course. nuclear weapons could be sued to destroy it, but care would be needed to make shore it did not fragment it.
He showed us software that predicts collision chances and one that assesses the size of an impact for different objects and speeds.
All in all a very interesting evening.
Venus Express and Mars Express - Dr Andrew Coates
Tonight we were fortunate to have Dr Coates of the Mullard Space Science Laboratory, University College London. He was a little delayed by the M25 so while we were waiting Eddie showed us an animation of the Sun he had taken through his web cam using the club's solar scope. it showed a prominence changing over the course of an hour and a half.
Dr Coates then arrived and began his talk. He first went through how Venus differs from Earth, despite being virtually the same size. It has a n atmosphere that consists largely of carbon dioxide with sulphuric acid mixed in. it has a run away greenhouse effect which heats its surface to 470 degrees centigrade and it has a surface pressure ninety times that of the Earth. Its day is almost the same length as its year, it rotates the other way to the Earth and it has no magnetic field. This means that the solar wind is ale to strip off parts of its atmosphere.
He discussed the probes that had actually been there. The Russian Verona probes actually landed and managed to operate in the hostile conditions for up to twenty minutes, sending back pictures of the rocky and barren surface.
Messenger, a probe, on its way to Mercury, passed Venus, at 0:08am BST yesterday morning. Venus Express, the subject of tonight's talk, is also currently in orbit around it, so it is the first time two probes have been in orbit around the planet at the same time. Messenger took reading of the solar wind upstream of Venus, which will be used to complement the readings from Venus Express.
As Venus's atmosphere is opaque at visual wavelengths, the surface can not be observed. However when Cassini p0assed on its way to Saturn, it discovered that there is a window in the infrared region. The European probe, Mars Express had suitable instrument for observing this, so Venus Express was built to the same design, which cut down on cost and design time.
Venus has been mapped using radar from Earth, but it is now being mapped in much more detail by Venus Express. It is also doing experiments on Venus's ionosphere, ho wit loses atmosphere to the solar wind and any evidence of current volcanic activity.
He then showed a comparison between Mercury, Venus, Earth and Mars, showing how the magnetic fields, or lack o fit, cause the atmospheres to behave differently. It also affects how the solar wind interacts with each planet.
He then went on to talk briefly about Mars and Mars Express. Mars currently has several probes both in orbit and on the surface. Mars Express is looking for evidence of water. Cosmic rays hit the surface and release hydrogen from underneath which may well come form water. Frozen patches have also been found and there is evidence of recent flows.
Yet again this was another very interesting evening.
Wednesday 13th June 2007
The evening started with Terry showing a movie of a pass of the ISS that he had taken on Monday night. He also showed some images he had taken of he Sun through the Club's Hydrogen-alpha and Calcium-K telescopes. He then run a movie that Eddie had take of a prominence on the Sun.
Andy then did the CPAC News. he started by comparing the rise of racing driver Louis Hamilton to a nova. He explained how nova, bright flaring of stars occur. Basically in a twin system, matter form one is captured by the other and builds up to a point where a reaction occurs causing the star to flare.
He then did a story about a very cool brown dwarf that had been discovered by a tem of scientist actually looking for quasars which are much further away, but can look very similar. Brown dwarfs are failed stars which got hot, but not hot enough to start the fusion required to power a star. They are anything from thirty to fifty times the size of Jupiter and only a tenth as hot as our Sun. Studying this one will lead to a greater understanding of star and gas giant formation.
He then spoke about the first images that have been taken of a star similar in size to the Sun. Apart from monster red giants like Betelgeuse, most stars appear as point sources of light, even through the most powerful telescopes. By combining four telescopes together you can create a giant virtual scope the size of the distance between them which has the resolving power of a scope that size, but not the light gathering ability. Using such a technique, they imaged the nearby star Altair and showed that it spins much faster than the Sun and is flattened at the poles into an oval shape as a result.
Finally he told us about a new super supernova which has been observed in the galaxy NGC1610. This incredibly bright object has sustained itself much longer than an ordinary supernova which occur at the end of the life of a blue giant star. The exact mechanism is still being debated. He rounded off with a diagram showing the evolution of different star types.
Wednesday 20h June 2007
Was Einstein 100% right? - Professor Malcolm MacCallum
Professor MacCallum went through both the Special and General Theories of Relativity indicating where observation had proved the theory to varying degrees of accuracy. These included the orbit of Mercury, light being bent from distance stars by the Sun during eclipses, the Global Positioning System and many others.
The only things that do not appear to fit in with the theories is a slight slow down in the Pioneer 10 and 11 spacecrafts as the left the solar system. Whether this is due to faulty observations or a genuine effect is not yet known.
A very interesting and through provoking evening.
Wednesday 27th June 2007
The evening started with Mike handing out a questionnaire to Members asking what they liked about the club, would like to se improved and ideas for next year's programme.
He then said that the Perseids meteor show would be upon us on 13th August and the Club would be organising a meteor watch out at our dark site.
he then went through how meteors originate. Out in the far reaches of the Solar System is the Oort Cloud. This is a collection of millions of objects, most of them a few miles across which are collections of ice contaminated with rocks. they have been likened to dirty snowballs. Sometimes the orbits of these become perturbed by collisions or near misses and one fo the them will go into a very elongated elliptical orbit around the Sun and becomes a comet.
As the comet approaches the Sun, it begins to melt and vent gas and particles. These should form a halo around the comet and initially they do. However the Solar wind then carries the particles away from the comet to form a tail. These can be millions and sometimes tens or even hundreds of millions of miles long. They always stream away from the Sun so when the comet is moving back out from the Sun, the tail will be in front. Sometimes there can be two tales as the lighter and heavier material becomes separated.
The tails of comets leave tiny rocky particles around the comets orbit. When the Earth passes through these they enter the Earth's atmosphere and the shockwave causes them to burn up and superheat the air leaving a brief luminous trail through the sky which we see as a meteor. Random meteors occur on most nights, but when we pass though a dense clump of these, often on a certain date of the year, we get many more than usual, often appearing to radiate fort he same point in the sky. These are known as meteor showers. if there are a lot, they are known as meteor storms. A count of the hourly rate can be taken and sent to the BAA.
The best way to observe meteor is to go to a dark site and take a reclining chair. It is important to wrap up warm even in summer. The best time to see them is after midnight when the side of the Earth we are on is moving into the swarm and not away from it.
Meteors also ionised the atmosphere so VHF and UHF radio signals can be bounced off them. People will listen for sudden bursts of distant commercial or amateur radio signals which would normally be over the horizon.
Several stories of meteor watches past were recounted including one year when Eddie and Pete went half way across the country to Wiltshire during the November Leonids to find ah ole in the Cloud, but were rewarded with a storm of 1500 an hour.
Life on Mars - Dr Michael Leggett
Tonight Dr Leggett gave us a talk on Life on Mars. Not the retro BBC1 drama series, but the prospect of organisms either having lived or currently living on the Red Planet.
He started by going through the history of ideas about life there. In early times there was a belief that all the planets had some kind of life on them. Later own it was believed that the prospect for life on Mars were slim. Later on an Italian astronomer noted he saw channels on Mars. He ascribed no organic origin to them, but the Italian word for channel is canalli which was mistranslated as canal.
Once this happened, a whole group of scientists, included Lowell, were convinced that they could see canals on Mars which they believed had been constructed by intelligent life on Mars in a desperate attempt to get water from the poles to the dry regions of what they thought was a dying planet.
Different scientist saw different patterns. Some some wide curved canals, others narrow straight ones. Some saw rivers and lakes. They believed dark areas could be vegetation or bodies of shallow water. Subsequent observations indicated that the bodies could not be water and the atmosphere was too thin for water or life, but the belief in canals persisted.
It also spawned an interest in possible Martian life in popular culture. This started with novels like H.G. Wells "War of the Worlds", Edgar Rice-Burroughs "Warlords of Mars" and Ray Bradbury's "The Martian Chronicles". it persist to this day through albums, films and books. Modern authors like Ben Bova are writing books about colonisation and even terraforming.
In reality, little about possible life there could be surmised until probes were sent. Many failed, especially Russian ones, but probes like the Viking Landers sent back good data in 1976. They were designed to look for life. The chemical experiments indicated no life, but the biological ones indicated there might be. The results are still being debated.
Some evidence has been gathered from meteorites that have come from Mars to Earth. One of these appeared to have life inside it, but this is still being hotly debated.
NASA have decided to look for by "following the water" on the basis that where there is water, there is life. There is good evidence that there is currently water in Mars, both locked in the polar caps where it is mixed with carbon dioxide and below ground. Occasionally disturbances release some of this underground water and it flows briefly on the surface before sublimating. (My note: this has happened in the last few years as two pictures taken a few years apart of the same place by one of the orbiters show no flow in the first picture, but a flow a few years later in the second.)
There is also evidence that Mars was much warmer and wetter in the past and had lots of surface water in lakes, rivers and streams. It has had three periods. A warm wet one many billions of years ago, a drying period, and he current cold, very dry one.
It is possible that life could have go going in the warm and wet period and adapted to the harsher conditions later on. After all, life can live in very harsh conditions on Earth. it can even live miles underground in solid rock and this may be the case on Mars today.
There is also traces of methane in the Martian atmosphere. As this degrades quite quickly, it must have something replenishing it/As there appears to be no volcanic activity on Mars, it could be either currently life, or deposits of methane left by previous life.
We plan to send more probes there to look for life. However even if we find what appears to be life, we have to ask, is it contamination brought by the current or previous probes from Earth. Did it hitch a ride on a meteorite from Earth?
It was asked what impact it would have on Earth's culture if life was found there. There would probably be an initial discussion, but eventually interest would return to normal levels.
Before any samples of Mars can be returned to Earth, it would be checked on Mars to make sure there was no harmful organisms in it. It would be tested again in Mars orbit and Earth orbit before being allowed back to Earth itself and even then, it would be held in the strictest quarantine as indeed the Moon rocks and astronauts were when they first returned.
A fascinating subject and this is an exciting time in Martian exploration.
11th July 2007
Mike started of the evening by going through the summer programme. Next week would be “Five go mad in Australia”. This would consist of Mike, Jim, Dave and Wendy recounting their adventures down under.
After that there would be not meetings at the Church until 5th September. In the meantime we will meet at the pub and there will be ten pin bowling on 29th August.
Andy Turner then did the CPAC News. The first story had been supplied the Royal Toilet Correspondent (yours truly) and was about an asteroid that had been named Rayleigh. This was after Lord Rayleigh who had been one of the few nobles to win a Nobel Prize. He had no direct link with Rayleigh other than when his mother, who lived elsewhere in Essex, had chosen the title, she though it sounded nice!
Andy then pointed out some mistakes in an “Astronomy Now” article about the Sun. He was saying that the article indicated that Hydrogen Alpha telescopes saw adsorption lines. He said this was not strictly true as they were actually readmission lines that occurred after the adsorption took place.
The large southern sky object Eta Carini is dominating the news as it is believed it may be a giant supernova waiting to explode. It flares up from time to time and similar pre supernova activity has been seen in objects in other galaxies. “Soon” in this context could be anytime in the next 100,000 years! If it did go off it would be visible in daylight!
Andy then reported on a new project been set up by Dr Chris Lintott of “Sky at Night” fame. It was called “Galaxy Zoo”. The SLOAN digital sky survey had take pictures of a million galaxies and now needed then analysed. It wanted members of the public to log on to its web site, undergo a short tutorial and then look at pictures of galaxies to decide what type they were and which way they were rotating. The scientists do not have time to go through hem all so it may be that the person looking at the galaxy will be the first person to see it. George reported the website had crashed when he tried to due an overwhelming response to the appeal.
Mike then talked about the planned Perseids meteor watch, which would take place on August 11th and 12th at the dark site.
Mike then described how planispheres worked. These were simple analogue devices, which for any given date will show you what the sky will look like a t a particular time. They can also predict sunset and sunrise times. They are set to cover ranges of latitudes so you have to make sure that you choose the right one. Also one suitable for use in red light is a must so avoid any that have red writing or graphics on them.
Andrew mentioned that comet Linear was currently visible in Ursa Major at about magnitude 7.8 so it should be an easy binocular object.
The evening was rounded off with Eddie showing how he had imaged some recent passes of the ISS with a web cam. At the time of filming, the Shuttle and a Progress 19 supply rocket were docked. It took him a few attempts to get the techniques and exposure right. He finally took an AVI of about 3000 frames and go about 40 frames that had the ISS in them as he was hand guiding and it moves very fast across the sky. It also gets bigger as it approaches the zenith. The detail you can see in the images is amazing.
Wednesday 18th July 2007
Five go mad in Australia – Mike, Dave Jim and Kevin (Wendy)
Back in April, the intrepid quartet above decided to make a trip to New South Wales in South East Australia to view the wonders of the Southern Skies. They spend three weeks touring around the area observing, visiting observatories and doing some sightseeing as well.
They started in Sydney. When they got there, they found that whilst they had booked four rooms, only three were available so two of them had to share. They did a boat trip around the famous harbour and Wendy climbed the famous bridge. He said you had to wear a special over suit and you could not take your own gear on to the bridge in case you dropped anything on the cars below.
They hired two cars. They were originally both supposed to be four wheel drive, but the car hire only had one of these in stock so they ended up with one four wheel drive and one saloon car.
After a few days in Sydney they headed inland into the Blue Mountains. These derive their name from the blue haze put into the atmosphere by the eucalyptus trees. The Blue Mountains are part of the dividing line of mountain ranges, which separates the relatively wet eastern coastal strip of Australia from the dry and arid Outback where sometimes it does not rain for years at a time. Outside of the Sydney the roads are empty and as the Australians drive on the same side we do, travelling around is very easy. Some of the roads are not always in very good condition however so care must be taken.
They visited a glowworm cave, which was fascinating. Unfortunately erroneous directions led them to walk for hours on the other side of the caves to the wrong car park. They also visited some other underground caves to look at the geology.
They visited Lightening Ridge, which is an opal-mining town and a bit like the Wild West. People register a claim to a piece of land and mine for opals. Some strike it rich, but many don’t. People have also built strange dwellings and follies here. One of these is a monument to astronomy.
On the observatory front they visited the famous Parkes Observatory, which was the subject of the film “The Dish” and is where the first pictures to come back from the Apollo 11 mission to the Moon were received. It is now home to several radio telescopes and radio telescope arrays.
They also visited the Siding Spring Observatory in the Warrumbungle National Park near Coonabarabran. Siding Spring Observatory has several telescopes on the site including the 2.3m Advanced Technology Telescope, the world famous 3.9m Anglo-Australian Telescope (soon to be only the Australian Telescope as the British are pulling out), 2m Faulkes Telescope, the 1.24m UK Schmidt Telescope, two Boller & Chivens Cassegrains 1m and 0.6m along with the 0.5m Automatic Patrol Telescope and 0.6m Uppsala Schmidt Telescope.
Dave gave us a brief tour of the wildlife that they saw including some very good photos of birds, which are Dave’s specialities.
They also did some serious observing. Mike and Jim took collapsible Dobsonian reflectors, specially designed to be lightweight and easily assembled and disassembled to fit in luggage. The base of Mike’s was damaged in transit, but duct tape and splints made of pencils fixed them.
Wendy took a 66mm refractor and Dave took a small spotting scope and a DSLR with very long lenses.
Dave said it is difficult to polar align in the Southern hemisphere as there is no Pole Star or other obvious reference points. He had to align through star trails, which can take up to an hour and a half to do properly. Despite this he took some spectacular photographs. These included upside down images of Orion, (it is down there), the Milky Way including the centre of it, Eta Carini, Omega Centuri, a star cluster bigger than the Moon in the sky, the Coal Sack nebula and other delights. He did not know for certain if any of them had come out until he came home as they are difficult to view on the camera screen and he was not able to take a laptop.
Wendy did sketches and these were of photographic quality, especially when he scanned them in and reversed the black pencil on white paper drawings into white on black images.
Mike also did sketches, but these were more of the aide memoir type. He combined hem with observing notes. However when he compared them with pictures from the net, he notices that his sketches were quite accurate.
All in all it seemed a fascinating trip.
Coffee Evening - All
This was the first Evening back after the summer break and is normally fairly informal. Mike welcomed us all back. He gave a summary of the Perseids meteor watch that the Club held at our dark site on the weekend of the 12th and 13th August. It was very well attended. We saw about a hundred meteors on the Saturday night and over four hundred between us on the Sunday night/Monday morning. It was a very enjoyable weekend and we were blessed with clear skies and no Moon.
He then went through some astro news. This included the clearest ground based images yet taken of the Ring Nebula and M13 using the Lucky technique which involves taken lost of images of the object and using software to pick the best pictures and bits of pictures and compiling them together.
He also said that a large patch of completely empty space, a billion light years across, had been discovered in the constellation, Eridanus.
George then showed us some pictures he had take of the meteors from both the dark site and Billericay.
Wednesday 12th September 2007
The sky was clear and there was no Moon so we looked at it through telescopes!
Wednesday 19th September 2007
Uranus - Me
Tonight I did a talk on Uranus. Firstly I showed its position in the Solar system and gave some facts and figures about it. It is the seventh planet from the Sun and the third largest by diameter. It is larger in diameter but smaller in mass than Neptune. Its orbit is: 2,870,990,000 km (19.218 AU) from the Sun. Its equatorial diameter is 51,118 km (32,190 miles). Its mass is 8.683 10 to 25 kg . It orbits the Sun once every 84.01 Earth years. Its day is 17 hours 14 minutes long.
Uranus is the ancient Greek deity of the heavens. He was the earliest supreme god and the son and mate of Gaia. He was the father of Cronus (Saturn) and of Cyclopes and Titans (predecessors of Olympian gods).
It was discovered by William Herschel on 13 March 1781. While he was scanning the sky with a 7-inch reflecting telescope, he observed an unusual object showing an extended disk-like shape. He thought he had discovered a comet, but he continued his observations and calculations for some months and discovered its orbit lay well beyond the orbit of Saturn and was fairly circular. It had actually been seen many times before but ignored as simply another star. The earliest recorded sighting was in 1690 when John Flamsteed catalogued it as 34 Tauri.
Herschel named it "Georgium Sidus" (Georgian Planet) in honour of his patron King George III. The French called it "Herschel". The name "Uranus" was first proposed by Johann Elert Bode in conformity with other planetary names from classical mythology, but it didn't come into common use until 1850.
Once discovered it remained largely a mystery. The planet's rate of rotation could be estimated only roughly and was believed to be anywhere from 16 to 24 hours. Most planets spin on an axis nearly perpendicular to the ecliptic, but Uranus' axis is almost parallel to it so which is the North Pole? Either its axial inclination is a bit over 90 degrees and its rotation is direct, or it's a bit less than 90 degrees and rotation is retrograde.
Five moons were discovered. These were Titania by Herschel in 1787, Oberon by Herschel in 1787, Ariel by Lassell in 1851 , Umbriel by Lassell in 1851 and Miranda by Kuiper in 1948 .All are named after characters from Shakespeare or Pope. All of then remained tiny points of light about which nothing was known. A system of nine narrow rings went undetected until 1977 (or did they…..)
Only one probe has gone there and there are no more planned. Voyager 2 had a flyby on January 24, 1986 at 09:59 PST (17:59GMT). Its closest approach was 81,500 km (50,600 miles) above Uranus'cloud tops. Voyager data showed that the planet's rate of rotation is 17 hours, 14 minutes. It imaged the five largest moons and also detected 11 previously unseen moons. It also studied the system, both the previously known rings and two newly detected rings.
Uranus has 27 known moons. There are 21 named moons and six unnamed ones. They are divided into three distinct classes. There are 5 large moons, discovered pre Voyager, 11 dark inner moons discovered by Voyager and 11 recently discovered much more distant moons. These may be captured objects from the Kuiper belt.
Miranda is the fourteenth moon in order of distance from Uranus. It is named after Prospero's daughter in Shakespeare's play “The Tempest”. It is also known as Uranus V. It was discovered on 16/2/1948 by Gerard Kuiper at McDonald Observatory.
Ariel is the fourth largest and brightest moon. It is the 15th moon in order from the planet. It is named after the leading sylph - a creature made of air – in Alexander Pope's poem "Rape of the Lock" (a name shared by the mischievous spirit who serves Prospero in Shakespeare's The Tempest). It is also known as Uranus I. It was discovered on 24/10/1851, at the same time as Umbriel, by William Lassell.
Umbriel is the third largest and darkest moon . It is the 6th moon in order from the planet. It is named after the "dusky melancholy sprite" in Alexander Pope's poem "The Rape of the Lock". It is also known as Uranus II. It was discovered by William Lassell on 24/10/1851, at the same time as Ariel.
Titania is the largest moon. It is 17th in order from the planet. It was discovered on 11/1/1787 by William Herschel Named for Queen of the Faeries in Shakespeare's “A Midsummer Night's Dream” . It is also known as Uranus III.
Oberon is the second largest moon It is 18th in order from the planet. It was discovered by William Herschel on 1/11/1787. It is named after the king of the Fairies in Shakespeare's “A Midsummer Night's Dream” It is also known as Uranus IV.
Puck is the 12th moon in order from the Planet. It is named after one of fairies in Shakespeare's “A Midsummer Night's Dream”. It is also known as Uranus XV. It is one of 10 new moons discovered in 1986 from images sent back by Voyager 2. It was the only one found soon enough to allow further images of it to be captured by spacecraft.
The rings were discovered from Earth in 1977 when Uranus occulted a star (or were they?). There were dips in the brightness of the star before and after it passed behind the body of Uranus which suggested it was surrounded by at least 5 rings. Four more were suggested by subsequent occultation measurements from Earth. Two additional ones were found by Voyager 2, bringing the total to 11.
On February 22, 1789, Sir William Herschel reported “A ring was suspected". He drew a small diagram of a ring and noted it was "a little inclined to the red". The Keck Telescope in Hawaii has since confirmed this to be true. Herschel's notes were published in a Royal Society journal in 1797 and promptly forgotten until they were rediscovered very recently.
Why were they not seen in the intervening years? Rings can darken due to dust. It has been observed on Saturn’s rings by Cassini. Therefore they may have been brighter in 1789 which was before the industrial revolution. Light pollution and smog may have prevented subsequent observers from seeing them.
Also there was a cold snap on Earth called the Maunder Minimum, (1645-1715) which saw temperatures that were on average 5 degrees below today’s. This might have removed water vapour from the atmosphere, locking it up as ice. If the climate was still relatively cold by the time Herschel made his observations, less water vapour may have made skies clearer and therefore more suitable for astronomy.
As expected, the dominant constituents of the atmosphere were hydrogen and helium. Amount of helium, about 15%, were considerably less than the 40% suggested by some Earth-based studies. Methane, acetylene and other hydrocarbons exist in much smaller quantities. Methane in the upper atmosphere absorbs red light, giving Uranus its blue-green colour.
The atmosphere is arranged into clouds running at constant latitudes, similar in orientation to the more vivid latitudinal bands seen on Jupiter and Saturn. Winds at mid-latitudes blow in the same direction as the planet rotates, just as on Earth, Jupiter and Saturn. Winds blow at velocities of 40 to 160m/s (90 to 360 mph); on Earth, jet streams in atmosphere blow at about 50m/s (110 mph) Radio science experiments found winds of about 100m/s blowing in the opposite direction at the equator.
A high layer of haze, photochemical smog , was detected around the sunlit pole. The sunlit hemisphere was also was found to radiate large amounts of ultraviolet light, a phenomenon that Voyager scientists have dubbed "dayglow". The average temperature is about 60K (-350F). The minimum near the tropopause is 52K (-366F) at the 0.1-bar pressure level. (The boundary between stratosphere and troposphere which is lowest level of atmosphere, comparable to the region on Earth where life abounds. One bar is the average pressure at sea level on Earth)
The illuminated and dark poles, and most of the planet, show nearly the same temperature below the tropopause. Voyager instruments did detect a somewhat colder band between 15 and 40 degrees latitude, where temperatures are about 2 to 3K lower. Temperatures rise with increasing altitude, reaching 150K (-190F) in the rarefied upper atmosphere. Below this level, temperatures increase steadily to thousands of degrees in interior where the material becomes liquid and eventually solid.
After Voyager there were no more probes. Earth based observations improved dramatically however. Uranus’s year is 84.01 Earth years so we have only observed it in detail since 1986. Twenty one years is one quarter of its orbit. Conditions there have changed in that time.
Hubble and Keck have made detail observations showing Uranus is warming up and becoming active with its weather as the moves towards its "spring" equinox and more of the planer gets evenly warmed. Extra rings and moons have also been discovered.
Uranus's rings appeared edge-on to Earth in August 2007. They will be completely edge on in December 2007 allowing a unique viewing opportunity for Hubble and Keck.
The edge-on perspective is considered favourable for seeing particular features in the rings. It makes the outer rings that contain centimetre to metre sized rocks seem dimmer as they obscure each other; but those that are normally almost transparent layers of dust become more visible as material merges into a thin band along the line of sight. Images revealed that the inner rings of micron-sized dust have changed significantly since Voyager 2 photographed them 21 years ago. The inner rings are now much more prominent than expected
Uranus can be observed by amateurs. Its brightness is between magnitude +5.5 and +6.0, so it can be seen with naked eye as a faint star under dark sky conditions. It can easily be found with binoculars. From Earth, it has an apparent diameter of four arc-seconds. In larger telescopes bigger than 12" (30cm), it ppears as a pale blue disc with distinct limb shading. Two of the larger satellites, Titania and Oberon, may be visible. Even in large professional instruments no details can be seen on its disc, although there is now a challenge to image it with CCD.
Wednesday 26th September 2007
A.G.M and Beginners Evening
We held the usual brief A.G.M. Mike, Ted and myself gave brief reports. We were then re elected.
Terry then gave a very interesting demonstration of his new 8" Mead Light Bridge Dobsonian telescope.
Debate - All
In place of the debate we had an evening reviewing the Kelling Heath Astrocamp.
Wednesday 10th October 2007
As it was clear, we had an observing night. We were joined by the Guides and Rangers from the adjoining church hall for the early part of the evening. Terry, Ed and me stayed until 11pm as the sky was clear. We were trying out Terry's new Meade Lightbridge.
Wednesday 17th October 2007
Mars Part 1 - Mike Culley
I had the lurg this week so could not attend, but I am sure Mike did an interesting talk on Mars.
Wednesday 24th October 2007
As it was cloudy, tonight was a beginners' evening.
Mike started with some news items.
He started with news about a short period comet 17/P Holmes which would normally be magnitude 17. Today at lunchtime (British time) it flared up to magnitude 3 and should be an easy naked eye object near the zenith in Perseus. It has no tail, but is a bright fuzzy ball when viewed through binoculars or a telescope. We just need clear skies now to see it.
He discussed the Peruvian meteor crater. It was 20m across and had been caused by quite a large object. Initial reports indicated that many locals had been poisoned by the impact. It seems now only a few people fell ill and this may be due to aground water contaminated by naturally occurring arsenic being disturbed by the impact.
He then talked about the fact that for the first time in history, both the Space Station and the Shuttle were being commanded by women at the same time.
He mentioned the Hipparcos mission which had been used to measure distances to stars. It had made some distances, such as those to the Pleiades, quite different to the previously accepted ones. It has now been found this was due to errors in the probes behaviour due to external influences. These have now been factored out and the distances now appear to be correct.
After a break, I did the main talk of the evening on "How the sky works". This was an explanation of what constellations are why the sky changes during the night and during the year, the ecliptic, stellar co-ordinates and how the Moon and planets move though the sky. If you would like a copy of the presentation, please let me know.
Wednesday 31st October 2007
Comet Watch - All
This was due to be the second part of Mike's Mars Talk. However as it was clear and Comet 17/P Holmes was still very visible, it was decided to hold an observing night.
Comet Fest - Andy Turner and all
In a change to the advertised programme, we decided to have an evening dedicated to comets and in particular Comet 17/P Holmes, the current "star" of the sky. Mike has prepared a PowerPoint presentation on comets, but due to a nasty does of the lurg, he dropped by briefly to delver the presentation and accompanying slides and then departed for his bed.
Andy was press ganged volunteered into delivering the talk. Using Mike notes and his own encyclopaedic knowledge gave a talk on the subject which was excellent, especially considering the thirty second notice he was given!
The word comet comes through the Latin comata which is derived from the Greek word kom meaning hair. The astronomical symbol for a comet is still a ball with hair. the Greeks noticed that unlike planets which always stayed confined to the zodiac, comets could appear anywhere in the sky. They believed them to be stellar rather than sky objects, but did not know much else about them. Aristotle recorded all this.
A comet hit the Earth 65 million years ago. It may have been a contributing factor in the mass extinction of the dinosaurs although this is still a matter of debate.
Halley's comet is depicted in the Bayeux Tapestry when it passed in 1066. In the sixteenth century Tycho Brahe used parallax observations to determine that comets showed none so must be much further away than the Moon.
Halley was the first one to predict the return of a periodic comet and it was named after him.
Comets originate from the Oort Cloud, billions of small icy objects which form a halo up to two light years from the Sun. Occasionally these get perturbed and come into the inner solar system. Some go round the Sun once and then out again never to return. Others stay in the inner solar system and go round the Sun in highly elliptical orbits ranging form a few years to many hundreds of thousands.
Comets are composed largely of ice with other elements within them, mainly carbon based molecules. They are sometimes described as "dirty snowballs". They are the darkest things in the solar system. As they approach the Sun, their dark surface retains its heat and they warm up, releasing gases such as water vapour. These form a halo around the comet. The dark core is known as the nucleus, this is usually only a few kms across. The halo is known as the coma and can be hundreds of thousands of miles wide, sometimes even bigger than the Sun.
The lighter particles in the coma are swept away by the solar wind, forming a tail. this tail always goes away from the Sun, regardless of the direction that the comet is travelling, so if it is heading away from the Sun, the tail will be in front of the comet. The coma and the tail glow by reflecting the Sun's light although there may be some fluorescing occurring. Some times a blue tail going in a slightly different direction can be formed. These are ions fluorescing as they recombine with stray electrons. This tale can sometimes go out in a slightly different direction as its particles are lighter and even more influenced by the solar wind.
We then saw some images of comets including Halley's in 1986, Hale-Bopp in 1996 and McNaught in 2007. We also saw some pictures of comet Shoemaker-Levy 9 which broke up and hit Jupiter in 2004.
After the break, Andy did an introduction to 17/P Holmes. It was discovered by Holmes (no relation to Sherlock!) in 1862 when it suddenly flared up and became very bright. It did this again on 24th October this year when it went from magnitude 17 to magnitude 3, a brightening of one million times. It became a naked eye object near Delta Persei.
Reasons for the flare up are still being debated. It is unlikely to be a collision as it also happened in 1862 and the chances of a comet being hit once are remote, let alone twice. It is unlikely to be breaking up as there is nothing nearby to cause it and once again it would not have done the same thing in 1862. It is most likely due to out gassing, but the mechanism has still not been fully explained.
It is currently the biggest thing in the solar system and is bigger than the Sun. it has got noticeably bigger over the last two weeks. it had no tale, but as our position relative to it is now changing, signs of a tale are starting to appear. It could be that the tale is on the other side of it to us.
We then saw images of it from Ted, George, Peter, Dave and Eddie. We also saw some very good drawings from Kevin. The photos showed it moving through the sky and growing in size as the nights progressed. It also had an offset nucleus visible inside the coma.
All in all, a spectacular object and an excellent evening.
Wednesday 14th November 2007
The Sun Kings - Dr Stuart Clark
Tonight we were privileged to have an outside speaker. Rather than tell you all about it here, I have decided to go all multimedia on you. If you go to
you can see the same talk given to Gresham college as a transcript, or if you scroll below it, an audio or video file.
It was an excellent talk and well worth a look of you missed it.
Wednesday 21st November 2007
As it was cloudy, tonight was a beginners' evening. I was not there, but a Mars night was held. George showed images form the Viking Missions to Mars and Ron showned some from the MER explorations.
Wednesday 28th November 2007
Astroquiz - All
Tonight I was quiz master for a six round astro quiz. I divided the assembled members into four teams. There were six rounds with ten questions in each round. The rounds were Planetary and Moon Features, Messier Objects, Constellations, Stars, Moons and Pot Luck. Teams could play a joker one round of their choice, part from on the last round. This gave them double points for that round.
After much fun, we ended up with three teams in second place, and one just ahead by four points to take the victory.
Drawing and Imaging Mars - Kevin Ellis and Pete Carson
In place of the advertised evening, Kevin showed the Club how to sketch Mars and Peter showed how to image it.
Wednesday 12th December 2007
As it was clear and there was no Moon, we had an observing evening. Favourite targets included Mars, M42 and the Christmas Tree Asterism. Despite the frost and freezing temperatures, it was an enjoyable evening.
Wednesday 19th December 2007
Mince Pies and good cheer was had by all.