The Summer Triangle is a fixture of summer skies. Its three stars are Vega, Deneb and Altair.
Our sky chart shows the Summer Triangle asterism as it appears at late evening. As seen from mid-northern latitudes, Vega – the Summer Triangle’s brightest star – shines high overhead around 10:00 p.m. daylight saving time (9:00 p.m. standard time). Altair resides to the lower left (southeast) of Vega, and Deneb lies to Vega’s left (east).
As the stars drift westward during the night, Deneb will swing upward, to replace Vega as the overhead star some two hours later, or around midnight. Of course, the stars aren’t really moving. It’s the Earth’s rotation that causes the stars to move westward during the night, and the sun to go westward during the day.
The three stars of the Summer Triangle shine so wonderfully brilliantly that you can see them from light-polluted cities. Or on a moonlit night. A bright waning gibbous moon will rise at early evening tonight, but these Summer Triangle stars will be able to withstand tonight’s drenching moonlight.
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