Welcome to the September night sky. This is the month of cooler evenings and longer, darker nights in the northern hemisphere. The Sun crosses the celestial equator on September 22 heading southwards, and this event is called an Equinox; this means that the whole world will experience equal length days and nights at this time.
On the first day of September, there will be an annular solar eclipse only visible from central Africa, but because the Moon’s orbit is, therefore, close to the ecliptic, the following full Moon will partially enter into the shadow of the Earth and this will make the full Moon of the 16th slightly less bright than usual.
September 8 sees the 50th anniversary of the first episode of Star-Trek on TV, and then three short years later the first man on the Moon. It’s a shame that manned space exploration has not progressed faster, as it has the potential to spark our imaginations and give hope for the future.
Two meteor showers this month are in the northern sky: The Epsilon Perseids on the 7th and Alpha Aurigids and the 23rd. Both these showers could be affected by moonlight, but the Alpha Aurigids at least have a reputation for fast-moving meteors that leave a smoke trail behind.
September is not a good month for planets, with Jupiter, Venus and Mercury having gone down over in the west and with Mars and Saturn in the early evening getting lower in the southwest. But the rings of Saturn are still a fine sight in any small telescope, and on the 8th the first quarter Moon will be just above Saturn aiding in its identification. The red planet Mars is now quickly moving eastwards away from Saturn and getting fainter.
The red giant star Antares is between Mars and Saturn and slightly lower in the sky and it is easy to tell that Antares is a star as it will be twinkling quite strongly.
Mars and Saturn should be shining with a steady light. Saturn will be the uppermost of the three objects and it will have a slightly yellowish colour.
The moon is new on September 1, first quarter on the 9th, full on the 16th and last quarter on the 23rd.
By Clive Jackson
Clive Jackson is the Director of the Camera Obscura (next to the Castle in Tavira), specialising in education and public outreach.
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To see the July Sky Map click on the pdf link below