September 2007 astronomy events

Jupiter spends September in the southwest at sunset. It's close to Antares in the head of Scorpio. Jupiter's at eastern quadriture on the 4th, which is an astronomer's way of saying it's 90 degrees east of the sun. Aquila is close to the meridian at sunset. And the Great Square of Pegasus is high in the east and won't need long to reach the meridian.

Learn to identify Spica in Virgo early this month, then spot Mercury a bit left of it in the west later. Spica and Mercury will be in conjunction on the 22nd and it will be a very close one (about 0.1 degrees apart). The gibbous planet and the bright star should make a nice pair in a telescope view. Mercury reaches greatest elongation on the 29th. It's in the farther reaches of its orbit this time around (aphelion on the 17th) which will make for easier seeing in some places. That part of its orbit also angles a bit below the earth's plane. So that'll make it a great view from the southern hemisphere, but a mediocre one from north of the equator.

For those with binoculars or dark skies and good eyes, Uranus can be found in Aquarius a little below one head of Pisces. The planet reaches opposition on the 10th. That's when it's directly opposite the sun in the sky. It's also when Earth is closest to it. Actually, Earth is closest to Uranus on the 8th. The ellipses of the two planets' orbits aren't perfectly alligned with each other, so such discrepancies occur. The point is, look for Uranus this month for the closest and best view.

Mars rises around midnight near the stars of Taurus. The Hyades make a V. The asterism's brightest member is called Aldebaran. The red planet is pulling away from the Hyades this month and close to the feet of Gemini. Morning skywatchers will find Mars well placed much higher in the east. Mars is at western quadrature (90 degrees from the sun) on the 17th.

Brilliant white Venus shines in the east before sunrise. It's among the faint stars of Cancer. As September progresses, the brighter stars of Leo and the planet Saturn become easily seen below it. Venus, the star Regulus, and Saturn will line up nicely late this month. The lineup starts with Venus farther out from the other two, but closing in quick. Check every morning you can. On the 3rd of October, Venus and Saturn will form the base of a very flat isoceles triangle with Regulus at the apex.

The moon passes Mars on the 4th, Venus on the 8th, Saturn on the 10th, and Jupiter on the 18th. The last quarter moon on the 4th will appear very high in the sky to those in northern latitudes, because the moon in most northward in its orbit around that time. The first quarter moon two weeks later will appear very low because the moon is southward. Likewise, from southern latitudes, the last quarter moon will appear low and the first quarter moon will appear high.

Parts of Antarctica, South America, and nearby ocean realms will experience a partial solar eclipse on the 11th. The greatest eclipse, up to 75% coverage, occurs at sunrise in a place shown on some maps as the Bellingshausen Sea. Click here for a visibility map.

The autumn equinox occurs September 23rd at 9:51.