Castle Point Astronomy Club
Castle Point Astronomy Club Diary
April 2018 by Dave Stratton
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Wednesday 4th April 2018

Andrew said that next week we have a quiz if we are not observing.

Ron announced that we have been given a 70mm refractor to add to our stock of scopes available free of charge to our members.

Peter said there will be an occultation of an 11th mag star on 20/21st April by an asteroid, which happens to have two satellites – details available.

He also said that Saturn is featuring a new white blob.

Apparently Amazon is marketing a solar filter that attaches to the rear of an eyepiece - How dangerous is that?

Mike introduced Gord for his talk:

How do planets move as they do? And Why do planets move as they do?

He also called it ‘EPPUR SI MUOVE’ which I guess is Italian for the lines above.

Well I thought long and hard about how to commit this to paper and in the end chickened out.

It was possibly the best presented talk I have heard – just full of detail and humour - all done without a note and no pictures and even a few equations but totally absorbing.

Very briefly it explained how and why the superior planets appear to have occasional retrograde motion and therefore apparently move backwards in their orbits.

Various learned people such as: - Aristarchus, Ptolemy, Copernicus, Tycho Brahe, Johannes Kepler, Galileo Galilei and Isaac Newton got a mention for their varying views on whether we went around the Sun or everything went around us also why we did not see parallax when looking at stars.

Very simply it is because we are on an inferior planet - we move faster and overtake our superiors and therefore view them from an ever changing place – with regard to the stars’ lack of parallax they are an awful long way away.


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