June is here. In the N. Hemisphere, the days are long, the sun is at its most intense for the year, and the weather is warm, but not as warm as it will be later this summer. And the summer sky is with us, too. The famous asterism known as the Summer Triangle is ascending in the eastern sky on these June evenings.
The Summer Triangle is not a constellation. Instead, this pattern consists of three bright stars in three separate constellations – Deneb in the constellation Cygnus the Swan, Vega in the constellation Lyra the Harp, and Altair in the constellation Aquila the Eagle.
Learn to recognize the Summer Triangle asterism now, and you can watch it all summer as it shifts higher in the east, then finally appears high overhead in the late northern summer and early northern autumn sky.
An asterism isn’t the same thing as a constellation, by the way. Constellations generally come to us from ancient times. In the 1930s, the International Astronomical Union officially drew the boundaries of the 88 constellations we recognize today.
On the other hand, asterisms are whatever you want them to be. They’re just patterns on the sky’s dome. You can also make up your own asterisms, in much the same way you can recognize shapes in puffy clouds on a summer day.
But some asterisms are so obvious that they’re recognized around the world. The Summer Triangle – a large triangular pattern consisting of three bright stars in three different constellations – is one of these.
So watch for the Summer Triangle. On June and July evenings, you’ll find it in the east at nightfall. It swings high overhead in the wee hours after midnight and sits rather high in the west at daybreak.
Bottom line: It’s nearly summer in the Northern Hemisphere. Look for the Summer Triangle – three bright stars in three separate constellations – ascending in the east on June and July evenings.
Deborah Byrd created the EarthSky radio series in 1991 and founded EarthSky.org in 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. "Being an EarthSky editor is like hosting a big global party for cool nature-lovers," she says.