Skywatch Line for Wednesday, September 13th, and Thursday, September 14th, 2017

This is the Dudley Observatory Skywatch Line for Wednesday, September 13th, and Thursday, September 14th, written by Louis Suarato.

The Last Quarter Moon occurs at 2:26 a.m. Wednesday. The Moon will reach perigee, its closest distance to Earth during this lunar cycle, at 12:06 p.m., also on Wednesday, at a distance of 229,820 miles. The average distance of the Moon to Earth is 238,855 miles, or about 30 Earth diameters. The furthest distance the Moon travels from Earth is 252,088 miles, or about 32 Earth diameters. At its closest, the Moon is 225,623 miles away, or between 28 and 29 Earth diameters. The Moon will set at 2:27 p.m., and rises again at 22 minutes past midnight as a 40% illuminated, waning crescent. Jupiter is only 10 degrees above the west-southwestern horizon at civil twilight. Look for Saturn about 25 degrees above the south-southwestern horizon as the sky darkens. Saturn sets at 11:13 p.m. in the southwest. Saturn reaches its eastern quadrature on Thursday. That is when a planet is perpendicular to the Sun, and receiving its light at a right angle. This angle creates long shadows and gives the ringed planet a 3 dimensional appearance through telescopes. This is equivalent to the Moon during the First and Third Quarter phases. Saturn’s rings are tilted at an angle of 26 degrees toward Earth, the most in 15 years. When the Moon rises overnight, you will notice its location between the constellations Gemini and Orion. The Moon is also in the middle of the asterism known as the Winter hexagon. The stars that comprise this asterism are; (clockwise from the Moon’s left) Pollux in Gemini, Capella in Auriga, Aldebaran in Taurus, Rigel in Orion, Sirius in Canis Major, and Procyon in Canis Minor. Look 25 degrees to the left of Procyon, and 16 degrees above Venus for M44, the Beehive Cluster, in Cancer. Binoculars will reveal the Moon is in the foreground of four open star clusters. Look for M35, and NGC 2129 above the Moon, NGC 2175 between M35 and the Moon, and NGC 2169 to the Moon’s right. Venus rises in Leo at 4:08 a.m., followed by Mercury at 5:02 a.m., and Mars, 8 minutes later. This is Mercury’s best morning appearance of the year as it is a day past its greatest western elongation, about 18 degrees from the Sun.

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