Skywatch Line for Friday, January 17, through Sunday, January 19, written by Sam Salem
This is Dudley Observatory’s Skywatch Line for Friday, January 17, through Sunday, January 19, written by Sam Salem.
On Friday, Sun rises at 7:22am and sets at 4:49pm; Moon sets at 9:32am and rises at 8:57pm.
The closest approach of Saturn and Venus will fall on Friday and Saturday evenings. The planetary pair will make an eye-catching sight.
On Friday, watch Venus and fainter Saturn in the southwest during and after dusk. They appear just 2¼° apart. That’s about the width of your thumb at arm’s length. Saturn is left of Venus.
On Saturday evening, Venus and Saturn are 2.2° apart, just a trace closer together than they appeared on Friday evening. Saturn is now lower left of Venus. From now on Saturn will move away farther below Venus.
Venus, magnitude –4.6 in the constellation of Aquarius, shines very high and bright as the “Evening Star” in the southwest during twilight, and lower in the west-southwest as evening grows late. It doesn’t set until about 2½ hours after dark. Venus is enlarging week by week as it swings toward the Earth, while waning in phase as it swings closer to our line of sight to the Sun. It has already enlarged to 25 or 26 arcseconds from pole to pole. It’ll be twice that size by the time it turns to a thin crescent plunging down near winter’s end.
On the other side of the sky in the southeast, Sirius twinkles brightly below Orion. Around 9 pm, Sirius shines precisely below Betelgeuse in Orion’s shoulder.
Watch Mars shift position night by night to line up with Castor and Pollux on Thursday and Friday. Mars is at opposition this week, glaring at magnitude –1.4 near the Cancer-Gemini border below Castor and Pollux. It comes into view as a steady orange spark low in the east-northeast in twilight. Mars shows best in a telescope from late evening through the middle of the night, when it’s very high toward the southeast or south. It is 14.6 arcseconds in apparent diameter when was closest to Earth on January 12th. Opposition took place on the 15th. But this is a relatively distant opposition for Mars. It’s near the aphelion of its elliptical orbit, the orbit’s farthest point from the Sun.
Jupiter shines at a bright magnitude –2.7 in the constellation of Taurus. It dominates the high east to south during evening, with fainter orange Aldebaran, fainter white Beta Tauri, and the Pleiades nearby.
Right after dark, face east and look very high. The bright star there is Capella, the Goat Star. To the right of it, by a couple of finger-widths at arm’s length, is a small, narrow triangle of 3rd and 4th magnitude stars known as “The Kids.” They form an asterism with Capella.