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Hal Kibbey

Last modified: Wednesday, August 28, 2013

Star Trak: September 2013

Aug. 29, 2013

BLOOMINGTON, Ind. -- Dazzling white Venus will come into view low in the west-southwest as evening twilight fades during September. On Sept. 8, about 45 minutes after sunset, the crescent moon will be just below Venus with the bright white star Spica less than 2 degrees to the lower right (west), forming a lovely trio as darkness falls.


Photo courtesy of NASA


Print-Quality Photo

Saturn will begin the month about 18 degrees to the upper left (south) of Venus, but each night the two planets will appear closer together. On Sept. 19, brilliant Venus will pass 4 degrees south of yellow Saturn. The two will then separate, and by month's end Saturn will be 13 degrees to the right (west) of Venus.

Jupiter will rise around 2 a.m. local time at the beginning of the month. Each week it will be visible about a half hour earlier, and it will be high in the east by the start of dawn, among the stars of the constellation Gemini the Twins. A telescope will provide magnificent views of the giant planet and its four bright moons first recorded by Galileo.

Mars will appear low in the east by 4 a.m. local time in September, and it will be significantly higher by the start of morning twilight. On Sept. 8-9, the red-orange planet will pass through the Beehive star cluster. Binoculars will provide the best view of this event.

Mercury will be barely above the west-southwestern horizon a half hour after sunset this month for viewers at mid-northern latitudes. Only those with an unobstructed view of the western horizon will be able to see it at all.


On a clear September night, you may be lucky enough to see an aurora (sometimes called "northern lights"). These silent ribbons and curtains of light can appear whenever the sun is active, but they are especially likely from August to October. Eruptions from the sun's surface hurl enormous amounts of charged particles into space, and when some of these solar particles head in our direction, they cause auroral activity. Details and photographs are available in a gallery. You can watch for auroras when they are most likely to happen by checking Spaceweather and National Weather Service sites. Sightings of auroras are reported on the Solar Terrestrial Dispatch website.


The sun will arrive at the September equinox on Sept. 22 at 4:44 p.m. EDT (20:44 Universal Time), marking the start of autumn in the Northern Hemisphere and spring in the Southern Hemisphere. For the next six months in the Northern Hemisphere, the nights will be longer than the days.

Moon phases

The moon will be new on Sept. 5, at first quarter on Sept. 12, full on Sept. 19 (the Harvest Moon, which is the full moon closest to the September equinox) and at third quarter on Sept. 26.