The Summer Triangle is a formation of stellar bodies called an asterism, made up of the bright stars Vega, Deneb and Altair.

Don't miss the stars of the Summer Triangle twinkling in the eastern sky this weekend

Source: space
Source Link: https://www.space.com/stargazing/dont-miss-the-stars-of-the-summer-triangle-twinkling-in-the-eastern-sky-this-weekend