Mars vs. Anti-Mars
Shining bright red in the heart of the constellation Scorpius, 1st-magnitude star Antares is often mistaken for Mars. In Greek, "Antares" means "rival of Mars" or "anti-Mars," so-named because it is about the same brightness and color as the Red Planet. As September comes to a close, the rivals are converging. Jeff Dai sends this photo of Mars and Antares setting side-by-side behind Mount Balang in Sichuan, China:
"I was looking southwest in the evening sky on Sept. 20th when a conspicuous pair of ruddy objects grabbed my attention," says Dai. "Red planet Mars is moving in for a close encounter with its ancient rival, the red supergiant star Antares."
On Sept. 28th and 29th, the nights of closest approach, Mars and Antares will be only a few degrees apart, a conjunction tight enough to fit behind your outstretched palm. Sept. 29th is the best night to look because the Moon will join the display, lining up to form a near-vertical column of heavenly bodies just above the southwestern horizon. Sept. 27th is a good night, too, but for a different reason: A slender crescent Moon will pass very close to Saturn not far from Antares and Mars.