This week, the waxing gibbous moon will race from Sagittarius to Virgo and become the second full moon of August Friday night. According to modern folklore, the second full moon in a calendar month is called a blue moon.
Stargazers can look for the Summer Triangle early in the evening this weekend before the moon rises too high and spoils their view of the sky. The brilliant star shining directly overhead at 9 Saturday night is Vega, the brightest star in Lyra the Harp. Vega is one of three bright stars that outline a large triangle that rides high in the southern sky throughout the summer and into the autumn.
The other stars in the triangle include Deneb and Altir. Deneb, found in Cygnus the Swan, is also overhead and about 20 degrees to the east or left of Vega. About 40 degrees below Deneb sits Altair, the brightest star in Aquila, the Eagle. These three stars outline the asterism known as the Summer Triangle.