The moon begins the month at waning gibbous phase, among the stars of Taurus. Sept. 3, the Pleiades share the spotlight, rising just before midnight. Last quarter occurs Sept. 4, with Mars three degrees south Sept. 6; this is also when the moon reaches perigee of 368,259 kilometres.
Sept. 8, the moon is 0.5 degrees north of the Beehive Cluster (M44), and later on occults Jupiter in the daytime sky. The next day, Regulus is 0.6 degrees north of the moon, while new moon occurs Sept. 10. Venus is occulted Sept. 14 for Southern Hemisphere viewers; the close-up event is a poor showing for Northern Hemisphere viewers, though, as the bright planet hugs the horizon at sundown.
Sept. 17, Antares takes the stage, hovering just 0.6 degrees north of Luna, another occultation in the south. First Quarter is on Sept. 18, with the moon at apogee of 404,221 km. The moon is at full phase Sept. 16 and once again among the stars of the Pleiades Sept. 30.
Mercury remains elusive for northern viewers owing to the tilt of the ecliptic at this time of year.
Venus is also plagued by the low ecliptic, in addition to being, at the same time, several degrees south of the ecliptic. Venus had reached greatest elongation east (GEE) in mid-August, and is heading toward inferior conjunction in late October. Experienced telescope users might find a challenge to see Venus south of the sun during daylight hours. Use extreme caution while viewing so close to the sun.
Mars rises in the east shortly after midnight, among the Gemini stars. The waning crescent moon passes to the north Sept. 6.
Jupiter rises in the east around 4 a.m., climbing the steep ecliptic (steep in eastern mornings; shallow in western evenings). The very thin crescent moon occults the gas giant Sept. 8th in a daytime event. This is the first of four monthly consecutive Jupiter occultations, with the remainder visible in the early morning before sunrise.
Saturn presents a good viewing opportunity, rising at sunset and crossing the sky all through the night. The full moon glides by Sept. 26.
Uranus is up all night among the stars of Taurus, The Bull. Sept. 10, the distant gas planet appears to stop its eastward movement, then apparently move westward. This is an illusion, of course, because it’s the faster Earth orbit that overtakes and moves past Uranus. This illusion puzzled ancient astronomers (and astrologers), because right up to Copernicus, it was thought that the Earth didn’t move–that it was the centre of the Universe. Copernicus and Kepler showed that the sun was at the centre and all the planets were in orbit around the sun.
Neptune is in the sky all night, leading nearby Saturn. The full moon is a few degrees away Sept. 26.
The zodiacal light is visible before eastern morning twilight for the middle two weeks of the month, beginning Sept. 9.
The autumnal equinox occurs in the late evening of Sept. 22.
James Edgar has had an interest in the night sky all his life. He joined The Royal Astronomical Society of Canada in 2000, was national president for two terms, is now the editor of the Observer’s Handbook, and production manager of the bi-monthly RASC Journal. The IAU named asteroid 1995 XC5 “(22421) Jamesedgar” in his honour and he is a Fellow of the RASC.
