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Summer Triangle in west on fall and winter evenings


Tonight for November 18, 2013

Moon and Aldebaran

The Summer Triangle is found in the west on these November evenings but if you look in the other direction at mid-evening on November 18, you’ll see the waning gibbous moon with the star Aldebaran.

The Summer Triangle is the signature star formation of summer, but you can see it in autumn, too – even in tonight’s blinding moonlight. The Summer Triangle showcases three brilliant stars – Vega, Deneb and Altair – in three separate constellations. Although December is less than two weeks away, the Summer Triangle will still shines in the western evening sky (at mid-northern latitudes or farther north). What’s more, the Summer Triangle will continue to shine after dark throughout December and January. Look for it tonight at early evening, high in your western sky.

November 2013 guide to the five visible planets

In the month of June – around the June solstice – the Summer Triangle pops out in the east as darkness falls and shines all night long. But now – in late November – the Summer Triangle appears quite high in the west at nightfall. As evening deepens, the Summer Triangle descends westward, with all three of its stars staying above the horizon for several hours after dark.

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Here is the Summer Triangle asterism – three bright stars in three different constellations – as photographed by EarthSky Facebook friend Susan Jensen in Odessa, Washington. Thank you, Susan!

Depending on where you live, Altair – the Summer Triangle’s most southerly star – will set around 10 to 11 p.m. tonight. Notice where you see the Summer Triangle at a given time this evening. The Summer Triangle will return to this same place in the sky some 4 minutes earlier with each passing day, or 2 hours earlier with each passing month.

As the Summer Triangle sinks low in the western sky around mid-evening, turn around to see Orion – the signpost constellation of winter – rising in the east.

Easily locate stars and constellations during any day and time with EarthSky’s Planisphere.

Bottom line: Look westward this evening for the three brilliant stars of the humongous Summer Triangle: Vega, Deneb and Altair.

Summer Triangle captured on July 9, 2012 by EarthSky Facebook friend Annie Lewis in Madrid, Spain. She said she took this photo of the Summer Triangle shortly after nightfall. In fact, she said, the only stars visible to the naked eye when I took the photo were the three in the Triangle, but her camera knew better! Thanks, Annie.