Star Trak: October 2017

BLOOMINGTON, Ind. -- Brilliant white Venus and red-orange Mars were 2.5 degrees apart against the background stars of the constellation Leo the Lion on Oct. 1. Venus rose 13 minutes before the much fainter Mars. The gap between the two planets closed until Oct. 5, when they were separated by just 0.2 degrees, about half the diameter of the full moon.

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Saturn and its moon Titan. Photo by NASA

Saturn will glow low in the southwest during evening twilight all October, dropping lower each week. It set more than three hours after the sun at the beginning of the month and will set an hour earlier by month's end. Saturn's rings will be tilted 27 degrees to our line of sight, the maximum angle possible. Saturn's largest moon, Titan, will be due south of the planet on Oct. 21 and due north on Oct. 13 and 29.

Mercury was out of sight as it passed behind the sun Oct. 8, moving from the morning to the evening sky. It will become visible again at dusk around the middle of next month.

Jupiter was visible for just the first few days of October, very low in the afterglow of sunset, before disappearing into the solar glare. It will then pass through conjunction with the sun on Oct. 26. In the second week of November it will return to visibility low in the east at dawn.

Meteor shower

The Orionid meteor shower will peak before the first light of dawn Oct. 21, just two days after new moon. Viewing conditions in a clear sky should be ideal, and viewers can expect to see close to the maximum rate of 20 meteors per hour.

The Orionids appear to originate from the 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 was full on Oct. 5 and will be at third quarter on Oct. 12, new on Oct. 19 and at first quarter on Oct. 27.

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