Wednesday, August 8, 2012

Saturn and Mars and the star Spica

It's a beautiful time of year for looking at the stars, and a beautiful time of the month for looking at them as well, with the moon out of the sky until after midnight each evening, providing brilliant views of the summer constellations.

Right now as you look to the west, there is a spectacular triangle low in the sky above the horizon, formed by the planets Saturn and Mars and the bright star Spica (part of the constellation Virgo).

They are unmistakeable, forming a near-equilateral triangle tonight, but their geometry will be changing rapidly over the next few nights. This excellent video from Tony Flanders, the cheerful and informative associate editor of Sky & Telescope, gives a nice animation of what will take place as Mars continues to close the gap with Saturn and eventually passes in between Spica and Saturn.

That video also provides some discussion of the upcoming Perseid meteor showers. Here is a link to a previous post discussing this wonderful annual meteor event, and here is a link to a different previous post which contains a diagram and directions for locating the constellation Perseus.

It is well-worth the effort to go outside and look at the triangle formed by Saturn, Mars and Spica. Ancient mythology often encodes the approach of two or more planets, sometimes adding details about the background constellations through which they are moving as they pass one another. This previous post discusses that concept, with examples.