THE SOUTHERN HEMISPHERE

Welcome Mercury back to the evening skies and discover celestial treasures in Grus, the Crane

When to use this chart

1 Sep at 00:00 AEST (14:00 UT) 15 Sep at 23:00 AEST (13:00 UT) 30 Sep at 22:00 AEST (12:00 UT)

The chart accurately matches the sky on the dates and times shown for Sydney, Australia. The sky is different at other times as the stars crossing it set four minutes earlier each night.

SEPTEMBER HIGHLIGHTS September sees the best return of Mercury to the evening skies for 2021. This elusive world is rarely visible outside twilight hours, but mid-month is placed 10° above the western horizon at the end of astronomical twilight. Travelling with the bright star Spica (Alpha (_) Virginis) for the last two weeks, Mercury is located below Venus. Its change in phase is also impressive; starting the month with the shape of a nine-day-old Moon, it reduces to that of a three-day-old crescent.

STARS AND CONSTELLATIONS September is a great time for observing; the spring nights are fairly long – and getting warmer – and being at equinox (on 22 September), we can view a wide selection of targets. The early evening shows Sagittarius, the Archer, and Scorpius, the Scorpion riding high on the back of the Milky Way. If you stay up all night, the predawn sky reveals Orion, the Hunter, with Taurus, the Bull in the north and the Magellanic Clouds in the south.

THE PLANETS

A western sky view reveals Mercury close to the horizon as twilight ends, with Venus higher up. Having just passed opposition, Saturn and Jupiter dominate the northern evening sky, with Saturn transiting (due north) at 21:00 mid-month, and Jupiter following an hour behind. Neptune trails later at opposition and is visible all night. Uranus rises in the evening and is viewed in the morning.