September 1999

by Steve Stefanik

As this September begins the sun is setting earlier, the constellation Sagittarius is on our meridian, the constellation Scorpius is past it, and the planet Mars is low in the southwest at nightfall. The "Summer Triangle" marked by the bright first magnitude stars Altair, Vega, and Deneb in the constllations Aquilla, Lyra, and Cygnus are directly overhead.

You can locate +0.3 magnitude "red planet" to the right (westward) of the bright first magnitude red star Antares in the constellation Scorpius (the scorpion). The pair inch closer to one another during the month until they are within 2 degrees on the night of the 17th.

The dim planets of Uranus (magnitude +5.7) and Neptune (magnitude +7.9) may me spotted with a telescope among the dim stars of the constellation Capricornus (the sea goat) low in the southeast.

The good news is that the two giant planets Jupiter and Saturn are making their way into the evening sky amid the stars of the constellation Aries. Jupiter rises by 10 o’clock followed by Saturn less than an hour behind. Although they are about the same size, Jupiter is much brighter at -2.8 magnitude because it is the closer of the pair but Saturn is still very respectable at +0.1 magnitude. They will replace Mars and Venus as the evening planets and adorn the Fall and Winter nightsky in the months ahead. It is always interesting to observe the various belts and zones of Jupiter and the ever changing positions of its four largest moons and the mystical rings of Saturn. They should provide hours of enjoyment during long dark nights this winter.

Speaking of long dark nights, the sun crosses the celestial equator at 7:31 a.m. on September 23rd marking the first day of Autumn when equal hours of daylight begin a deficit until it reaches the Winter Solstice in December.

The planet Venus has become a "morning star" in the East rising an hour before sunrise at the beginning of the month and by more than three hours by the end of the month.

Mercury is lost in the glare of the sun this month and Pluto is of course too small and dim to be seen with all but the most powerful telescopes.

The moon will be "new" on the night of the 9th and "full" on the night of the 25th.