This is the Dudley Observatory Skywatch Line for Wednesday, June 22nd and Thursday, June 23rd written by Louis Suarato
Wednesday night, the stars comprising the asterism known as the Summer Triangle shine over the eastern horizon. Lowest, in the constellation Aquila, is Altair. At the distance of 16.7 light-years away, Altair is the twelfth brightest star in the sky, and one of the closest stars that can be seen with the naked eye. To Altair’s upper left, at the tail of Cygnus, the Swan, is Deneb. Deneb is also part of the asterism known as the Northern Cross. At an estimated distance of 2,600 light-years from Earth, Deneb is the 19th brightest star in the sky. The third vertex of the Summer Triangle is Vega, in the constellation Lyra. Look for Vega above Altair and Deneb. Vega is the fifth brightest star in the sky, and second brightest to Arcturus in the northern celestial hemisphere. Vega is 25 light-years from Earth and was the first star, other than the Sun, to be photographed.
Mars and Saturn are now separated by about 20 degrees over the southern horizon. Mars has the tallest mountain, and the longest, deepest, canyon in the Solar System. Olympus Mons is 13.6 miles above the Martian plain. That’s about two and a half times taller than Mount Everest. Valles Marineris canyon, named after the Mariner 9 orbiter that discovered it in 1971-1972, is 120 miles wide, and 4.3 miles deep. That’s about 4 times deeper that the Grand Canyon. Saturn, known as the “jewel of the solar system” because its ring system, has 62 known moons. Saturn’smoon, Titan, is second in size only to Jupiter’s Ganymede, as the largest in the solar system.
The 93% illuminated, waning gibbous Moon rises at 10:10 p.m. Wednesday, in the constellation Capricornus. I was recently informed of a Chronological Catalog of Reported Lunar Events, that was prepared for NASA by researchers that included Patrick Moore. The catalog details four centuries of observations of Lunar events, defined as temporary changes, such as the brightening of crater floors. The link to this fascinating chronicle can be found here: www.astrosurf.com/lunascan/papers/R-277.pdf.