Skywatch Line for Friday, October 1, through Sunday, October 3, 2021

This is Dudley Observatory’s Skywatch Line for Friday, October 1, through Sunday, October 3, written by Sam Salem.

On Friday, Sun rises at 6:53am and sets at 6:36pm; Moon rises at 1:00am and sets at 4:37pm. Before and during early dawn Saturday morning, look below the crescent Moon by about a fist at arm’s length for Regulus, forefoot of the constellation of Leo the lion. Before and during early dawn Sunday morning, the waning crescent Moon forms a flat, almost isosceles triangle, with Regulus and Algieba, or Gamma Leonis, to Regulus’s left or upper left.

Venus, brilliant at magnitude –4.2, shines low in the southwest during twilight. It sets around twilight’s end.

Jupiter, at magnitude -2.7, and Saturn, at magnitude +0.5, continue to shine in the southeast to south during evening. They sit 16 degrees apart on opposite sides of the dim constellation of Capricornus. During twilight, bright Jupiter, on the left, is slightly the lower of the two. They level out soon after dark, and later they tilt the other way, with Saturn now the lower one. Saturn sets around 2am, followed down by Jupiter about an hour later. In the evening look for 1st-magnitude Fomalhaut, two fists lower left of Jupiter.

Vega is the brightest star just west of the zenith after dark. Face west and look to Vega’s right, nearly a fist and a half at arm’s length, for Eltanin, the nose of Draco the Dragon. The rest of Draco’s fainter, lozenge-shaped head is a little farther behind. Draco always eyes Vega as they wheel around the sky. The main stars of Vega’s own constellation, Lyra, are faint by comparison. They extend about 7 degrees to Vega’s left.

Vega is the brightest star very high in the west. Arcturus, the brightest star in the constellation of Boötes, is getting low in the west-northwest. The brightest star in the vast expanse between Vega and Arcturus, about a third of the way from Arcturus up toward Vega, is Alphecca. The magnitude 2.2 star is the crown jewel of the small, dim constellation of Corona Borealis, the northern crown. Alphecca is a 17-day eclipsing binary. The periodic eclipses result in a magnitude variation of 2.21 to 2.32, which is hardly noticeable to the unaided eye.

During evening, look just above the northeast horizon, far below high Cassiopeia, for bright Capella on the rise. Capella, the brightest star in the constellation of Auriga, is the third brightest star in the northern celestial hemisphere after Arcturus and Vega. Its name meaning “little goat” in Latin.

The Big Dipper is perhaps the most famous of all star patterns. For latitudes of 41 degrees North or farther North, The Big Dipper is circumpolar, or always above the northern horizon. For latitudes below 41 degrees, the Big Dipper is below horizon during the evening hours in the autumn. For our area, look for the Big Dipper shining way up high in the sky on spring evenings, but close to the horizon on autumn evenings.

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