October 2001

By Steve Stefanik

October, the first full month of Fall, began with its evenings bathed in the golden glow of the Harvest Moon. Tonight, the waning gibbous moon will pass through the Hyades, an open star cluster which marks the head of the bull in the constellation Taurus. The moon rises about 8:45 p.m. EDT but wait until about 10 o’clock when it will be high enough above the eastern horizon to clear the treetops and buildings. If you observe the moon through binoculars you will be able to see hundreds of sparkling stars in the background beside the moon. As you continue watching you will see the moon overtake and occult or cover up several of the stars in the cluster. Minutes later the stars will reappear on the opposite side of the moon.

If you spend an hour or more watching the lunar occultation of the Hyades you may notice a very bright pale orange star rising below the Hyades. If you focus your binoculars on it you’ll notice immediately that it is not a star but the planet Saturn with its intricate ring system and miniature "solar system" of 20 or more moons. Currently its brightness is –0.1 magnitude and only 19.7 arc seconds in angular size but it will increase both in size and magnitude in the coming months as it approaches opposition.

While you are outside and if you have binoculars or even a small telescope, if you turn and face south you may be able to spot two more planets, Neptune and Uranus among the stars of the constellation Capricorn. Uranus is the easier of the two to spot at +5.8 magnitude. Neptune is considerably more difficult at +7.9 magnitude.

By this time the planet Mars is low in the southwest among the stars of the constellation Sagittarius. Although it is substantially dimmer than it was this past summer, it is still the brightest object in that part of the sky and you should not have difficulty spotting this deep red-orange orb. However, it has shrunk considerably in size and is now less than 10 arc minutes angularly and any detail on its surface is all but gone. We’ll have to wait another two years before it reaches opposition once again.

About the time Mars is setting in the west the giant planet Jupiter is rising in the east along with the constellation Gemini. You can’t miss it. It shines at –2.3 magnitude and is the largest in size of any of the planets at 40 arc seconds in apparent diameter. Through binoculars you can even see its four largest moons change position from one night to the next. Through a moderate size telescope you can watch its turbulent atmosphere change right in front of your eyes. It will continue to rise earlier and earlier and get larger and larger over the next five months on its way toward opposition.

If you are awake before sunrise, two more planets are visible in the east in the constellation Virgo. Venus rises by 5 a.m. and glistens at –3.9 magnitude. You can’t miss it! A waning crescent moon will be directly above it on the morning of the 14^th. By the end of the month the planet Mercury will join Venus in a spectacular conjunction. The pair will be within one degree of one another and remain together for ten days into November.

Don’t forget to turn your clocks back 1 hour on October 28 when we will go back to standard time.