The September 2023 Night Sky

Welcome to the September night sky. This is the month of the autumnal Equinox in the northern hemisphere. This means that the Sun is moving southward in the heavens and, on Saturday the 23rd, it crossed the celestial equator. It will at that time rise exactly in the east and set exactly in the west 12 hours later.

September is short on meteor showers with the Epsilon Perseids being the only noticeable one from the 5th to the 21st, with the peak on the 9th.

In the news mid-August was a discovery of a new comet by a Japanese astronomer called Hideo Nishimura from Kakigawa, Japan. The designation of this comet is C/2023-P1.

This comet has been found to have hyperbolic velocity, which means it is travelling too fast to be orbiting our Sun and, therefore, it comes from beyond our solar system. This may well be the first time this comet will be coming close to a star.

It was discovered on the night of August 12, and it is moving very quickly. It crossed Earth’s orbit on August 17 and will cross Venus’s orbit on the 27th. It will be closest to the Sun on September 18, at which time it will be inside the orbit of Mercury.

There is no chance of a collision between Earth and the comet as at its closest approach to us on September 13, it will be many millions of miles away.

It is not known how big the comet is or how bright it will become. It is expected to be easily visible with unaided eye, but you must get up very early in the morning, a couple of hours before the Sun rises, to see this comet at its best.

On the morning of September 11, it will be in the constellation of Leo and easy to find as it will be close to the crescent Moon, the planet Venus and the star Zeta-Leonis. The final brightness is not known, but it will certainly be visible through binoculars.

In mid-August, the comet was in Gemini but quite faint, and then it moved into Cancer, and in September, it will pass into Leo and then into Virgo. This comet may never be close to a star before it might break up and disappear, or it could flare up and become a dramatic unaided eye object in mid-September.

The planets Mercury and Venus are morning objects with Venus rising four hours before the Sun in mid-September. The gas giant planet Jupiter rises just after midnight in September, but the ringed planet Saturn is up all night this month visible high in the South.

Elon Musk’s Space X company plans to launch its Starship again on August 31. This rocket has had many upgrades and the chance of success now is getting closer to 100%.

The Moon is at last quarter on the 6th, new on the 15th, first quarter on the 22nd, and full Moon on September 29.

By Clive Jackson
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Clive Jackson is the director of the Camera Obscura – Tavira EYE attraction, located near the Castle of Tavira. Specialising in education and public outreach.
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To see the September Sky Map click on the pdf link below

2023-09 September nightsky