This is the Dudley Observatory Skywatch Line for Wednesday, June 26th, and Thursday, June 27th, written by Louis Suarato.
The 31% illuminated, waning crescent Moon sets at 2:08 Wednesday afternoon, leaving the sky moonless until it rises again at 2 a.m. Thursday. Mars and Mercury, now less than 3 degrees apart, set at 10:03 p.m., and 10:07 p.m. Wednesday. You’ll require binoculars, and a clear northwestern horizon, to see the two planets set side by side. Twilight finds Jupiter 15 degrees above the south-southeastern horizon. Saturn rises at 9:17 p.m., and sets at 6:33 Thursday morning.
The asterism known as the Summer Triangle can be seen above the eastern horizon at twilight. The Summer Triangle is comprised of Altair, in the constellation Aquila, Deneb, in the constellation Cygnus, and Vega, in the constellation Lyra. Vega, at a distance of 25 light=years, is the brightest of the three stars, with an apparent magnitude of 0.03. The second brightest star in this asterism is Altair, at a distance of 16.6 light-years, and an apparent magnitude of 0.77. Deneb is the third brightest star in the Summer Triangle, with an apparent magnitude of 1.25, and 3,550 light-years away.
During the summer months, when the darker side of Earth faces the center of the galaxy, the brightest constellations in our skies are Cygnus, Lyra, Aquila, Scorpius, Sagittarius, and Hercules. A highlight in Cygnus, in addition to Deneb, is the binary star Albireo. Even small telescopes will split this pair into one gold star and one blue star. Lyra features Vega, the third brightest star in our sky. In about 12,500 years, Vega will replace Polaris as Earth’s North Star. The Milky Way is also an occupant of Lyra’s southeast corner. Aquila is the home to our twelfth brightest star, Altair. Scorpius’ brightest star is red giant, Antares. Anares’ diameter is 7,000 times that of our Sun. Scorpius is also host to the Milky Way, and Messier objects M4, M6, M7, and M80. When you look at Sagittarius, you are looking at the cloud-like structure, which is the heart of the Milky Way. Hercules is one of the largest constellations in the sky. Its crown jewel is the magnificent globular cluster, M13.