Mars and its "rival," the star Antares (whose name means "rival of Mars), are a long way from each other, but the distance is decreasing as Mars moves eastward against the background of stars. Mars has two other bright companions now: the planet Saturn and the star Spica. This view is about one hour after sunset. The trio will remain fairly close together for a few more nights.
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Two legendary “rivals” are sharing the southwestern quadrant of the evening sky. Although they’re a good distance apart, they’re pretty easy to pick out because they’re both bright orange.
The most famous member of the rivalry is the planet Mars. It’s low in the west-southwest as night falls, and it forms a triangle with two other bright objects to its right — the planet Saturn and the star Spica.
Mars’s rival is far to its upper left: Antares, the brightest star of Scorpius, the scorpion. It’s almost exactly the same color and brightness as Mars, so the two really do look like a matched set.
In fact, the “rivalry” comes from that physical resemblance. Mars reminded ancient skywatchers of the color of blood, so they named the planet for the god of war — Mars in Rome, and Ares in Greece. And since the star in Scorpius looked so much like Mars, it was called Ant-Ares — a name that means “rival of Ares” or, in the Roman version, rival of Mars.
It’s a one-sided rivalry, though. Mars is quite small — only about half as big as Earth. It shines by reflecting sunlight, and gets its orange color from iron-rich sand and rock at its surface. Antares, on the other hand, is a supergiant star — one of the largest stars in the galaxy — thousands of times wider than Mars.
Mars will move closer to Antares over the next few weeks, making the rivalry even easier to see.
We’ll talk about another colorful object — a Blue Moon — tomorrow.
Script by Damond Benningfield, Copyright 2012
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