The Helix Nebula is one of our closest planetary nebulae, located 650 light-years from Earth in the constellation Aquarius. A planetary nebula is formed by an intermediate to low-mass star, which sheds its outer layers near the end of its evolution. Photo: MPAS member Chris Kostokanellis
Highlights this month
- 3SunVenus is stationary — resumes direct (eastward) motion. (1:17pm)
- 5TueThe Moon passes Jupiter — 3° apart. (3:42am)
- 5TueJupiter is stationary — begins retrograde (westward) motion. (5:51am)
- 6WedMercury in inferior conjunction with the Sun — lost in the glare. (9:05pm)
- 15FriMercury is stationary — resumes direct (eastward) motion. (10:20am)
- 19TueNeptune at opposition — closest and brightest of the year, up all night in Pisces (mag 7.8). (9:06pm)
- 22FriMercury at greatest morning elongation (18° from the Sun, mag −0.4) — best morning apparition. (11:05pm)
- 23SatSpring equinox.
- 27WedThe Moon passes Saturn — 2° apart. (1:14pm)
Be sure to enjoy the rich regions of Scorpius and Ophiuchus this month before they sink below the western horizon. Just above them lies an area around the heart of the Milky Way that’s brimming with star clusters and bright nebulae. In contrast, the eastern half of the sky is relatively empty, although you can still find several constellations, including Pisces, the Fishes; Cetus, the Whale; and Eridanus, the River.
Lying in the constellation Tucana, the Small Magellanic Cloud can be found close to the beautiful globular cluster 47 Tucanae, also known as NGC 104, which is a must-see target in the September southern skies. It is visible to the naked eye as a hazy star, while a small telescope shows its bright centre and many of its glittering stars. This cluster is 15,000 light-years away. Other visible targets include the globular clusters M22 in Sagittarius, NGC 6397 in Ara, and M4 in Scorpius. You can also see the open clusters M6 and M7 in Scorpius.
On September 18, Venus is at its greatest brightness and Mercury is at its highest altitude in the morning sky. This month’s conjunctions, which is when two astronomical objects appear close to each other in the sky, include the moon and Jupiter on September 5, and the moon and Saturn on September 27. On September 21 there is an occultation of the star Antares, which is when the moon passes in front of a star during the course of its orbit around the Earth.
Tickets for the Victorian Astronomy Convention are now on sale at the MPAS website. It is open to all interested members of the public, even if they aren’t part of an astronomy club. The keynote speaker is astrophysicist and cosmologist Dr Brad Tucker. Brad is a well-recognised and popular TV and radio presenter and an expert at communicating in simple terms all things to do with astronomy and space in Australia. Special guests will be OzGrav, with their amazing virtual reality headset system that takes people to a virtual universe full of planets, stars, black holes, and of course gravitational waves.
By Nerida Langcake
This article appeared in the September 2023 issue of the Mornington Peninsula Magazine.
The sky in detail — September 2023
Sun & twilight
| Date | Sunrise | Sunset | Day length | Astro. dark begins | ends |
|---|---|---|---|---|---|
| Fri 1 | 6:43am | 5:58pm | 11h 15m | 7:26pm | 5:15am |
| Sun 10 | 6:29am | 6:05pm | 11h 36m | 7:33pm | 5:02am |
| Wed 20 | 6:14am | 6:14pm | 12h 00m | 7:42pm | 4:46am |
| Sat 30 | 5:58am | 6:23pm | 12h 25m | 7:52pm | 4:29am |
Days lengthen by about 70 minutes over the month.
The Moon
- Last QuarterThu 7, 8:23am
- New MoonFri 15, 11:39am
- First QuarterSat 23, 5:36am
- Full MoonFri 29, 8:02pm
Apogee 12 Sep (406,100 km) · Perigee 28 Sep (360,100 km)
The planets
Rise/set for mid-month at The Briars.
| Planet | In | Mag | Rise | Transit | Set | Best |
|---|---|---|---|---|---|---|
| Mercury | Leo | 1.4 | 5:43am | 11:22am | 5:00pm | Hidden |
| Venus | Cnc | −4.6 | 4:20am | 9:46am | 3:12pm | Morning |
| Mars | Vir | 1.7 | 7:14am | 1:30pm | 7:46pm | Hidden |
| Jupiter | Ari | −2.5 | 10:23pm | 3:40am | 8:52am | Morning |
| Saturn | Aqr | 0.4 | 4:22pm | 11:03pm | 5:49am | Evening |
| Uranus | Ari | 5.7 | 11:02pm | 4:09am | 9:11am | Morning |
| Neptune | Psc | 7.8 | 6:21pm | 12:35am | 6:45am | All night |
Computed for The Briars, Mt Martha. Times are local (Melbourne).
Generated automatically from the MPAS sky engine on 15 July 2026.
The solar system — September 2023
Evening sky Morning sky Up much of the night Lost in the Sun’s glare
Open the full interactive orrery ↗ — fast-forward, pick any date, toggle the Moon and more.
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