Skywatch Line for Wednesday, January 18th, and Thursday, January 19th, 2017

This is the Dudley Observatory Skywatch Line for Wednesday, January 18th, and Thursday, January 19th, written by Louis Suarato.

The asterism known as the Winter Hexagon, or Winter Circle, consists of the stars Rigel, in the constellation Orion; Aldebaran in Taurus; Capella in Auriga; Pollux in Gemini; Procyon in Canis Minor; and Sirius in Canis Major. This asterism appears in the northern celestial hemisphere from December to March. The stars comprising the hexagon are some of the brightest in our winter night sky. Look over the eastern to southeastern horizon after 7 p.m. to locate this asterism. Sirius is the lowest, and brightest of these stars. Look counter-clockwise for Procyon, up to Pollux, higher to Capella, southward to Aldebaran, and down to Rigel. You will notice the Milky Way streaming through the center of this asterism. Among the Messier objects contained within the asterism are: M42, the Great Orion Nebula; M50, the Heart-Shaped Cluster in Monoceros; M38, the Starfish Cluster in Auriga; and M1, the Crab Nebula in Taurus.

Venus remains high and bright, shining a magnitude -4.47 above the southwestern horizon after sunset. Look for dimmer Mars 7 degrees to Venus’ upper left. The 57% illuminated, waning gibbous Moon rises about 15 minutes before midnightWednesday, followed by Jupiter 6 minutes later. Our Moon and the solar system’s largest planet will be separated by just 3 degrees. Try to see both in the same binocular field of view. Virgo’s brightest star, Spica, will be to 4.5 degrees to Jupiter’s lower right. The Moon reaches its Last Quarter phase at 5:14 p.m., Thursday. Saturn rises at 4:58 Thursday morning, followed by Mercury an hour later. Mercury reaches its greatest western elongation, 24 degrees from the Sun, at 5 a.m. Thursday.

January 19th is the birth date of German astronomer Johann ElertBode. Born in 1747, Bode discovered a mathematical relationship for the distances of planets from the Sun. Bode’sLaw, as it was later known, stated if the number 4 was added to the individual numbers in the series 0. 3, 6, 12, 24…, then divided by 10, the result was the astronomical unit distance of each planet from the Sun. His theory failed with the discovery of Neptune, which did not follow the formula.

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