September 1995

by Steve Stefanik

All eight of the other planets can be seen in the September evening sky.

The first two you should locate are Mercury and Venus, after the sun goes below the western horizon and before they set. Look for Mercury 11 degrees lower and to the right of the brightest star Spica in the constellation Virgo and 27 degrees to the left of the sun by scanning the western horizon with binoculars about half an hour after the sun sets on the evening of the 8/9th when it reaches greatest elongation (it's highest point above the horizon). Venus returns to the sky as an "evening star" after being behind the sun during the month of August. You've got to be prompt because it sets within 20 minutes after the sun sets. It shouldn't be too difficult to find this brilliant -3.9 magnitude beacon but if you do encounter difficulty it will be just below and to the right of a new waxing crescent moon on the evening of the 25th.

The next planet you should focus on is Mars. Far fainter (at magnitude +1.4) than either Mercury or Venus, look for the ruddy red planet near the bright star Zubenelgenubi in the constellation Libra. If you still need help look for it near a thin waning crescent moon on the night of the 27th.

Pluto is of course the dimmest (magnitude +13.8) and hardest of all the planets to locate because it requires a telescope with at least an 8 inch aperture and a camera and successive clear nights for viewing the change in it's position against the background stars. But, if you have the equipment and the patience you may find it among the stars in the constellation Serpens.

Somewhat easier to locate are the twin blue-green planets of Uranus and Neptune. Look above and to the east of the constellation Sagittarius in the south with your binoculars for the +5.7 and +7.9 magnitude pair.

The easiest of the planets to find is of course Jupiter. Look for the bright white -2.0 magnitude giant above the first magnitude red star Antares in the constellation Scorpius in the southwest as night falls.

Saturn is somewhat harder to find among the stars of Aquarius in the southeast. It is at its brighest for the year on the night of the 13/14th when it reaches opposition directly opposite us from the sun. Look for the magnitude +0.7 pallid orange planet between a circlet of stars and the bright first magnitude star Fomalhaut in the constellation Pisces. If you still can't find it look for it near the full Harvest Moon on the night of the 8/9th. Through binoculars or even a small telescope you will barely make out it's rings as a thin white sliver with several of it's moons lined up parallel to it's plane. This is because every 30 years the plane of the earth is lined up with the plane of Saturn's rings so they appear to disappear. We will pass through the plane of it's rings for the last time in this century in February 1996. Then we will be looking at the ring's southern face for the next 30 years.

We will reach the autumnal equinox on September 23rd at 8:13 Eastern Daylight Time when the sun will appear to cross the ecliptical plane of the planets once again giving us equal hours of daylight and darkness.