Mars is retrograde

I had the misfortune to hear the astrology on Steve Wright's show today. From this I learnt that Mars is in retrograde again, so it's not all bad. It irked me that Russel Grant, today's astrologer, kept saying the planet was going backwards. It's doing nothing of the sort, but it does look like it is, as shown here by the great Astronomy Picture of the Day team:

The fact that it looks like it's going backwards in the sky has nothing to do with how you should live your life, or that you should really save making decisions until Easter.

What this apparent backwards motion is doing is giving us evidence that the Earth, and other planets, orbit the Sun. This was one of the pieces of evidence Copernicus put forward when he argued against the notion that everything orbits the Earth. Here's a handy video to explain:



As a species we have been, and still are I would say, quite arrogant about our status in the Universe. As Carl Sagan said:



"It has been said that astronomy is a humbling and character-building experience. There is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world. To me, it underscores our responsibility to deal more kindly with one another, and to preserve and cherish the pale blue dot, the only home we've ever known."


Given that there are probably hundreds of billions of planets in our galaxy alone, there really is nothing special about Earth, except what we make of it.