The seasons change this month as the Sun crosses the celestial equator heading south. This marks the arrival of autumn in the northern half of the world and spring in the downunder. A little comet passes through the northern sky this month, inviting stargazers with binoculars to have a look. Venus makes a close approach to a bright star in the morning sky early in the month, and Mars makes a striking rendezvous with its rival, the star Antares, in the evening sky later in September. Here’s what to see in the night sky this month…
2 Sept. Saturn sinks in the southwestern sky as darkness falls early in September. It lies less than 10º to the west of red-orange Mars at the beginning of the month. This will be your last chance to see the planet this year with a telescope. It’s been a good apparition, with the rings generously tilted towards our line of sight by more than 20º. Even a pair of binoculars reveals Saturn’s largest moon, Titan, which has a chilly, hazy atmosphere and surface lakes of liquid hydrocarbons.
2 Sept. First Quarter Moon, 11:11 UT
5 Sept. Venus remains in the morning sky this month but moves eastwards, rising an hour before the Sun at the beginning of September and about half an hour before the Sun by the end. Today,Venus comes within 1º of the 1st-magnitude star Regulus low in the eastern sky about a half hour before sunrise. Jupiter shines well above them to the west. Venus outshines Jupiter, which is near its minimum brightness of magnitude -1.8.
4-5 Sept. Look for 6th-magnitude Comet C/2014 E2 (Jacques) in the same binocular field-of-view of the bright star Deneb in the tail of Cygnus, the Swan. The comet will look like a faint ball of fuzz with no tail just to the west of the bright star. On September 16, the comet will pass Albireo at the head of Cygnus. Here’s a map to help you follow the path of this comet through the month:
9 Sept. Full Moon, 01:38 UT.
16 Sept. Last Quarter Moon, 02:05 UT
17 Sept. Mars passes half a degree north of the star Dschubba (δ Scorpii) in the claws of the constellation Scorpius, the Scorpion. Look low in the southwest for this constellation in the northern hemisphere, and high overhead from the south.
21 Sept. Early risers can see Jupiter near the waning crescent Moon about an hour before sunrise.
23 Sept. At 02:29 UTC, the Sun crosses the celestial equator moving south. This marks the beginning of spring in the southern hemisphere and autumn in the north.
24 Sept. New Moon, 06:14 UT
27-28 Sept. Look for the astonishing sight of Mars coming within a few degrees of the bright orange star Antares (α Scorpii), the “rival of Mars” in the constellation Scorpius. This is a rare opportunity to see the two bright red-orange objects so close to each other. Mars will be slightly brighter. But which is redder?
29 Sept. Look for the waxing crescent Moon near Mars and Antares.