Castle Point Astronomy Club
1969-2019 - 50th Anniversary Year
Castle Point Astronomy Club Diary
January 2019 by Dave Stratton
Castle Point Astronomy Club


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Wednesday 9th Janaury 2019

Welcome to our first evening in 2019.

It´s our Social evening.

It was well attended.

We had a very keen couple in the form of Graham and his daughter Hannah and it was a delight to welcome Brandon and his lady friend Paddy. Brandon is the son of our late member Colin.

It was a typically cloudy evening so we were able to have a very good natter.

Rather satisfying.

Wednesday 16th Janaury 2019

Mike said that next week we would be treated to a slice of cake to celebrate the very first meeting of our club on 22nd January 1969 - 50 years ago!

Andrew will be giving a talk on Imaging with an iphone or we might be observing.

Ed said that next week early on Monday 21st there would be a Lunar Eclipse. Plus he had bought along several bits that we were invited to take as we wished. Also he said he had received a nice letter from Sandra Hobbs, daughter of our late member Bernard, thanking us for the help that was afforded her in selling her Dad’s astro bits last year.

Jim reminded us that the club’s selection of scopes was available to all members.

Mike introduced Gord for his talk:How Far Away Is It? And How Do We Know?

He posed the question – how do we tell something’s distance? Be it a candle, car or a star.

The further away they are the smaller they appear. He gave demos with images of candles and a coin.

He said the units we used to denote distance were varied and said that M31 the Andromeda Galaxy was 2.5m lya but this could be expressed as a mind blowing lot of miles -1,701,354,387,773,000 miles.

We have the AU – Astronomy Unit which is the distance of the Earth to the Sun 93 million miles or 1AU, then we have the light year (ly) 9.46 trillion kilometers miles then we have the Parsec 3.26ly.

How long is a meter? He said that in 1793 it was one ten millionth of the longitude quadrant going through Paris – which is 10,000Km long. In 1960 it was updated and is now defined as 1,650,763.73 times the wavelength of Kr86.

In 1983 the driver eye test was defined as the ability to read a number plate at 25yards.

He said that direct measurement as is done with a tape measure does not lend itself to great distances.

Radar Echo Timing is possible – the furthest object measured is Saturn.

Using Parallax is possible providing the object is close enough as the angles are so small. The Moon is just 20 and the Sun is the same apparent size but 400 times farther away. The nearest star is impossibly small.

If we use the Earth´s orbit to increase the base line the nearest star is just 10. More distant stars are too small to measure.

In this case in astronomy we use Standard Candles, a standard candle is a class of objects whose distances can be computed by comparing their observed brightness with their known luminosity. Cepheid variable stars are useful as standard candles because their pulsation period is related to their luminosity in a known way.

Gord explained that objects have the magnitude that we see (apparent magnitude) then we have their Absolute Magnitude. This is how bright they would be if viewed at 10Parsecs.

Cepheid variable is a type of star that pulsates radially, varying in both diameter and temperature and producing changes in brightness with a well-defined stable period and amplitude.

A strong direct relationship between a Cepheid variable's luminosity and pulsation period established Cepheids as important indicators of cosmic benchmarks for scaling galactic and extragalactic distances. This robust characteristic of classical Cepheids was discovered in 1908 by Henrietta Swan Leavitt after studying thousands of variable stars in the Magellanic Clouds. This discovery allows us to know the true luminosity of a Cepheid by simply observing its pulsation period. This in turn allows the distance to the star to be determined, by comparing its known luminosity to its observed brightness.

Polaris is our nearest Cepheid variable at 100 Parsec

Gord added that the Large Magellanic Cloud is 170,000ly away.

Edwin Hubble measured the distance to M31 at 1,500,000ly away it is actually 2.537 million lya and closing!

Gord made this wonderful!

Wednesday 23rd Janaury 2019

Andrew said that next week we have Dave Sm talking about Exo Planets and the following week we have an outside speaker Greg Smye-Rumsby with a talk on The History of Longitude at Greenwich.

Jim reminded us about the club scopes which are available to all members.

Ed said the club’s viewing of the recent lunar eclipse went well.

Mike said he had several dates for our diaries: Saturday 16th March - 7.00pm to 9.00pm Astronomy Open Night at Hadleigh Country Park.

Saturday 27th April – BAA Day at Sweyne Park School, Rayleigh – Topic: Galaxies.

Sunday 2nd June (Morning?) – Family Space Day at Hadleigh Country Park.

Saturday 5th October 7.00pm to 9.00pm – Astronomy Open Night at Hadleigh Country Park.

He came with two cakes to celebrate the 50th anniversary of the very first club meeting on 22nd January 1969.

Mike introduced Andrew for his talk: Astro Photography with an iPhone.

He said that friend used a smart phone with a lens ten years ago and was impressed.

He said the cameras in iPhones were actually very good. He showed us an old 5S model mounted on a tripod with a small scope attached to the phone – albeit a little insecurely. He said you had to be careful it did not fall off!

He showed us his first attempt from 13th June 2018 – the results were not terribly good.

The next try from 21st June was a bit better.

He said he had discovered a camera app called Nightcap which was only a few pounds to buy.

He showed us a slide of the screen and talked us through the multitude of settings – it even had AI.

It had a setting for imaging stars and even an ISS mode.

We saw an image of Mars taken at Canewdon on 6th August – it was rather small but sharp. He also had various images of constellations.

During a club observing evening on 26th Sept he had grabbed a super pic of the ISS streaking across the sky and a trail of lights from a plane in the same image. He even had M31.

On 13th Jan 2019 from his new home in Marks Tey he had a good image of Orion despite there being a lot of nearby lighting.

After modnight in the early hours of the 14th, he had some good images probably due to his increased confidence and knowledge of the best settings. He said that he was amazed at its ability to see the stars despite the obvious light pollution.

On 21st he had some images of the eclipse which suffered from poor focussing which he said was proving difficult.

He said his next steps would involve a telescope and a visit to our Dark Site.

Then we had cake and very nice it was too.

Mike hoped we could survive for another 50 – we can only do our best.

Wednesday 30rd Janaury 2019

Andrew said that next week we have our first outside speaker of the year in the form of Greg Smye-Rumsby talking about The History of Longitude at Greenwich.

Jim gave an advert to members to make use of the club’s scopes.

Ed mentioned the possibility of a Wallasea visit in the very near future on Saturday, Sunday or Monday - he will monitor the weather and advise via the usual means.

Mike introduced Dave Sm for his talk: Exoplanets

Dave began by saying that he was not actually very interested in Exoplanets but nevertheless decided to give a talk on them to learn more.

He explained that an Exoplanet or extra solar planet is a planet outside the Solar System. The first evidence of an Exoplanet was noted in 1917, but was not recognized as such. The first scientific detection of an Exoplanet was in 1988; it was confirmed to be an Exoplanet in 2012. The first confirmed detection occurred in 1992.

There are many methods of detecting exoplanets. Transit photometry and Doppler spectroscopy have found the most. In several cases, multiple planets have been observed around a star. About 1 in 5 Sun-like stars have an Earth-sized planet in the habitable zone. Assuming there are 200 billion stars in the Milky Way it can be hypothesized that there are 11 billion potentially habitable Earth-sized planets in the Milky Way, rising to 40 billion if planets orbiting the numerous red dwarfs are included.

With the aid of a slide of our solar system he explained that planets are hard to see because they are small and are only shine with reflected light from their star.

We heard about Giordano Bruno, 1548 – 17 February 1600 was an Italian Dominican friar, philosopher, mathematician, poet, and cosmological theorist. He is known for his cosmological theories, which conceptually extended the then novel Copernican model. He proposed that the stars were distant suns surrounded by their own planets and he raised the possibility that these planets might foster life of their own, a philosophical position known as cosmic pluralism. He also insisted that the universe is infinite and could have no centre. He got burnt at the stake!

Dave told us about Peter Van De Kamp who in 1960 thought he had discovered a wobble in Barnard’s Star which he presumed was due to a planet, this is now thought to have been caused by a fault with his scope.

The first Exoplanet was found by Aleksander Wolszczan a Polish astronomer in 1992. He is the co-discoverer of the first extra solar planets.

In 1995 Michel Mayer and Didier Queloz used the technique of angular velocity to find them.

In physics, the angular velocity of a particle is the rate at which it rotates around a centre point: that is, the time rate of change of its angular displacement relative to the origin. It is measured in angle per unit time, radians per second in SI units, and is usually represented by the symbol omega.

NASA's Kepler Space Telescope was an observatory in space dedicated to finding planets outside our solar system with a particular focus on finding planets that might resemble Earth. The observatory was in commission for just under 9 years, from its launch in March 2009 to its decommission on Nov. 15, 2018.

Dave said that direct observation work was being done by Gael Chauvin.

Indirect method – this is measuring changes in radial velocity – Doppler shifts indicate movement. The movement is caused by the gravitational pull of a planet.

Our ability to detect radial velocity has dramatically improved from 50m/sec to 1m/sec.

We saw some demos of the Doppler Effect with a video and also Dave used his phone which was emitting a fixed tone and as he moved the phone towards and away we could hear the change.

He said another indirect method was the Transit Method. This is only possible when the Exoplanet travels between the parent star and us. It simply blocks a small amount of light so the star dims fractionally. However this method only allows a detection rate of 0.47%.

We saw a video that helped us understand why the Doppler Effect works.

Dave said it worked with light waves as well as sound. It causes the wave to be shifted such that if the object is receding then the light is shifted to the red end of the spectrum and if it is approaching we see a shift to the blue end. So the terms red shift and blue shift are used.

Gravitational microlensing is an astronomical phenomenon due to the gravitational lens effect. It occurs when there is an massive object between the observer and the object being looked at.It can be used to detect objects that range from the mass of a planet to the mass of a star, regardless of the light they emit. Microlensing by an isolated object was first detected in 1989.

We saw a chart showing the the number of exoplanets known has increased dramaticall peaking in 2016.

As most of us know Dave is rather keen and very good at charting the light changes from variable stars so he decided not to actually find one by this technique but to see if he could pick up the changes from an Exoplanet that had been discovered by this technique.

We saw two sets of results and he was clearly successful.

He ended with a pic of his new scope a Celestron EQ8 and mount which he was thrilled to say he had been allowed to buy by you-know-who. He said the results to date are very good.


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