This is the Dudley Observatory Skywatch Line for Wednesday, May 16th, and Thursday, May 17th, written by Louis Suarato.
The 3% illuminated, waxing crescent Moon sets at 9:31 p.m. in the constellation Taurus. Venus, about 12 degrees above the Moon, sets at 10:45 p.m. to the lower right of Gemini. Thursday night, the 8% illuminated Moon will be 7 degrees to the left of Venus. Venus reaches perihelion on Wednesday, its closest distance from the Sun during its annual orbit. Venus orbits the Sun every 224.7 Earth days, and has the most circular orbit of all the planets. Its orbit ranges from 107 million kilometers to 109 million kilometers, giving it an eccentricity of .007, nearly a perfect circle, and only a 2 million kilometer difference from aphelion and perihelion. Open star cluster, M35 can be found about 4 degrees above, and between the Moon and Venus. Discovered by Philippe Loys de Cheseaux in 1745, M35 is a star cluster of 50 to 100 stars over an area equivalent to that of the Full Moon. This 5th magnitude star cluster is 2,800 light-years away. If the crescent Moon appears a bit larger, the reason is that lunar perigee, when the Moon is at its closest to Earth during this cycle, occurs Thursday at 5:05 p.m., when the Moon is 226,040 miles away.
Jupiter rises about an hour before sunset, and will be visible until dawn. Saturn rises at 11:22 p.m. in Sagittarius, flanked on the right by globular star clusters M22, and M28. Saturn’s largest moon, Titan, can be seen through small-to-medium sizedtelescopes. Titan is the second largest moon in the solar system, after Jupiter’s moon Ganymede. It is larger than Mercury, and 50% larger than Earth’s Moon. Mars rises at 1 a.m., becoming the last easily visible planet to appear during the night.
The Albany Area Amateur Astronomers’ monthly meeting will be held Thursday beginning at 7:30 p.m. at miSic in Schenectady. The meeting will feature the annual “Journal Club”, when members share presentations about astronomy related journal articles, books, equipment, and videos they have reviewed. Members and non-members are welcome.