October Skies - Thank You, Indiana University

From IU News Room - Indiana University

Three planets appear close in October sky


Oct. 2, 2009

BLOOMINGTON, Ind. -- Jupiter will reach its highest point in the southern sky soon after darkness falls during October. Normally this would be the best time to view the great planet with a telescope, but in this case the images may be blurred by turbulence. Earth's atmosphere cools rapidly after sunset as it loses its daytime heat, and this tends to produce unsteady viewing. Use low magnification for better images.

Red-orange Mars will be climbing the eastern sky soon after midnight, and it will be high in the southeast by the start of morning twilight. Beginning the month south of the bright stars Castor and Pollux in the constellation Gemini the Twins, Mars will cross into the constellation Cancer the Crab. By month's end the planet will approach the Beehive star cluster, a spectacular sight in binoculars or a low-power telescope.

Three planets will appear close together in the predawn sky in early October. Venus will be the first to rise, coming up two hours before the sun as a dazzling white "morning star" low in the east. Venus has probably provoked more UFO reports than any other object in the night sky, and it's easy to see why.

Mercury will follow Venus about 45 minutes later at the beginning of the month, much fainter but getting brighter each day. The small planet will be highest above the eastern horizon on Oct. 6, about a half hour before sunrise.

Last to appear will be Saturn, rising about 20 minutes after Mercury as the dawn sky brightens at the beginning of the month. The two planets will be closer each morning until Oct. 8, when brighter Mercury can serve as a marker for Saturn passing less than 1 degree above it. In the days following, Saturn will climb higher until it passes similarly close above brilliant Venus on Oct. 13. Saturn's rings were tilted edgewise to Earth in September, but their tilt to our line of sight will increase rapidly during October as Saturn continues to climb higher in our sky.

Meteor shower

The Orionid meteor shower will peak before the first light of dawn on Oct. 21. Moonlight will not interfere, so observers with a dark sky may see up to 30 meteors per hour. The Orionids appear to originate from the familiar constellation Orion the Hunter. Orion will rise before midnight in the east-southeast, and the number of meteors will increase as it gets higher above the horizon. The shower will be active for most of October, with the number of meteors gradually increasing from the start and declining after the peak. The Orionid meteors are dust particles from Halley's Comet, left behind in the comet's orbit.

Moon phases

The moon will be full on Oct. 4, at third quarter on Oct. 11, new on Oct. 18 and at first quarter on Oct. 25.



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