¡SkyCaramba! Weekly astronomy blog for the week ending July 26, 2014
This week, four bright objects are lined up in the south to southwest part of the sky. If you watch them over the next two months, you’ll see planets lining up with stars and you’ll have a great opportunity to identify them all.
After darkness sets in any evening this week, look to the south. You’ll find an orange star that is in the head of Scorpio. That star is called Antares and its name means the rival of Mars. When you’re looking at Antares, you’re looking toward the center of the Milky Way Galaxy. However, Antares is not in the galaxy’s center. It’s just in the line of sight.
A little west of Antares is Saturn. If you have dark enough skies, you may see that Saturn is in a diamond formed by four dim stars of the constellation Libra. Saturn looks yellow.
Keep going west and you’ll see another reddish object. That is Mars.
And a little farther west of it is a bright blue-white star called Spica. It’s the brightest star in Virgo.
Saturn is farther from the sun than Mars, so the ringed planet doesn’t move as fast as the red planet. So you won’t see Saturn moving much among the stars during the next few weeks. But Mars is moving eastward and around August 24th, it will be just south of Saturn. At that time, Mars will be 1.3 earth-sun distances from us and Saturn will be 10.1 earth-sun distances away.
Also at that time, all the objects in our current discussion will be in the southwest just after sunset. Spica will be close to setting. As more weeks go by, these stars and planets will scoot farther west. In early September, Spica will have set when you finally get a good view of Mars between Antares and Saturn.
By about September 27th, Mars will be north of Antares. Then, you can compare them side by side and judge for yourself whether the ancient Greeks and Romans were correct in considering them rivals. The Greeks called the planet Ares. The star, being near to Mars in color, was called Antares perhaps because people could mistake it for the planet. Roman gods in many cases were renamed Greek gods, but they didn’t feel the need to rename Antares. Jack Horkheimer of the PBS shows Star Hustler and Stargazer once said he’s really glad they didn’t rename it Antmars.
I wrote the above with a northern hemisphere bias, because that’s where I observe from. But let me note for my southern hemisphere readers, you will see these objects high overhead and arcing down the sky to the west this week. They’ll keep sliding down to the west from night to night, and you get to keep a pretty good view of Spica all the way into September. Mercury and Spica will be within a degree of each other on September 20th, so you get something extra to look forward to. I’ll enjoy it with you vicariously via a web cam or Stellarium.