1, summer triangle refers to the triangle composed of Vega in Lyra, Tianjin IV in Cygnus and Altair in Aquila in the southeast of summer. Even in a big city, as long as you avoid the strong light interference, you can see that this obvious geometric figure is Vega in the west of the triangle, four stars in Tianjin in the east, and Altair in the southeast. You can also find the splendid Milky Way in this big triangle, which extends outward from the triangle, traverses the north and south, and divides into two forks.

2. In summer nights, you can't see this summer triangle only on cloudy days. In the triangle, there is Vega in the west, four stars in Tianjin in the east and Altair in the southeast.