Oh, what a night! The mild evenings of September are perfect for planet and stargazing. Even better, we find that planets Venus, Jupiter and Saturn are bright and visible in the evening all month long!
At twilight, a nice series of conjunctions happens in the west his month.
On the 1st, dazzling Venus is to the upper left of Mercury, with that innermost planet very low but bright at exactly magnitude 0.0. On the 8th, look for Mercury below the thin crescent Moon.
On September 9, at dusk, the young Moon will stand to the upper right of Venus. The bright planet appears just about the horizon.
The crescent Moon and Venus. Credit: NASA/Bill Dunford
Then, on September 10, after sunset, look again for the crescent Moon; Venus appears to its lower right, very near the bright double star Spica. Mercury will be nearby, low near the horizon, though you may need binoculars to find it.
How the Moon and Venus will appear on September 10, 2021. Credit: NASA/JPL-Caltech
On Tuesday, September 14, Neptune reaches opposition. Neptune will be visible all night—so it’s as good as chance as any to spot Neptune. This is the only planet in our solar system that is not visible to the naked eye, so you will need a pair binoculars or small telescope. I’ll write more about Neptune’s opposition later.
This month, watch for Pegasus, the Winged Horse in the southeastern sky! A useful guide to this asterism (unofficial star pattern) is the Great Square, which outlines Pegasus’ body. See our star chart and how to find Pegasus.