How Do We Know That Venus Orbits The Sun?

  • John D. Clark
Part of the Patrick Moore's Practical Astronomy Series book series (PATRICKMOORE)

Venus exhibits phases like the Moon. It is a lot further away, so it looks a lot smaller than the Moon. The phases are not visible to the naked eye, except to a very few sharp-eyed people; and were unknown until the advent of the telescope about 400 years ago.

You cannot see the phases very well in 10 × 50 binoculars, but my 6 in. f/5 Newtonian telescope shows them very nicely. At least it did in late winter 2006. The crescent phase was unmistakable. But when it first appeared in the evening sky around January 2007, I was very puzzled because I had seen the phases so easily the previous winter just before sunrise. I could not see any phases. The darn thing was just a bright blob even at maximum magnification.

I told my wife, not very confidently, that it must be much further away than a year ago. Was I right?

It was about this time that I first tried my hand at photography with a webcam. My first photos were not a pretty sight. It took me a couple of months to get around to...


Circular Orbit Circular Motion Astronomical Unit Centripetal Force Stop Watch 
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Copyright information

© Springer Science+Business Media, LLC 2009

Authors and Affiliations

  1. 1.King’s Lynn, NorfolkUnited KingdomEngland

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