Skywatch Line for Friday, October 17, through Sunday, October 19, written by Sam Salem
This is Dudley Observatory’s Skywatch Line for Friday, October 17, through Sunday, October 19, written by Sam Salem.
On Friday, Sun rises at 7:11am and sets at 6:09pm; Moon rises at 3:10am and sets at 4:34pm.
On Friday morning, the waning crescent Moon shines near Regulus, the brightest star in Leo the Lion. Then, on Saturday morning, the crescent Moon floats between Regulus and the eastern horizon.
On Sunday morning, the crescent Moon hangs close to Venus. The thin Moon, just two days from new, shines about 4° to the upper right of Venus low in the east. Venus, magnitude –3.9, rises just before the beginning of dawn. Watch for it to come up due east.
On Saturday, Mercury and Mars are in conjunction, 2° apart, very low in the west-southwest in the fading afterglow of sunset. Use binoculars, or a telescope with low power to view the two planets, about 15 minutes after sunset. Mercury is the brighter of the two, at magnitude –0.2. Mars is only magnitude +1.5, a fifth as bright as Mercury.
Locate Mercury, move upward with the binocular, about a third the width of the view, and try for Mars.
Jupiter, magnitude –2.2 in the constellation Gemini, rises by midnight in the east as the morning hours advance. Castor and Pollux shine above it. By the beginning of dawn, the three stand very high in the south, with Procyon below them and Orion standing upright farther to their lower right.
Jupiter’s moons, Io and Ganymede, are both casting their little shadows onto Jupiter’s face on Sunday night from 2:42 to 3:18 am.
Saturn, magnitude +0.8, is up in the east-southeast as night falls. It climbs through the evening. Spot it lower right of the Great Square of Pegasus in early evening, and directly below the Square by the time Saturn transits the meridian, due south, around 11pm. In a telescope its rings remain very nearly edge-on.
Uranus, magnitude 5.6, in Taurus 4° from the Pleiades, is well up by 10 pm.
Neptune, magnitude 7.8, is a few degrees from Saturn. Use a finder chart to help you locate Neptune with respect to Saturn.
On Sunday, the Orionid meteor shower may already be active in the hours before dawn Monday morning. The shower’s radiant is at the top of Orion’s club. the Orionid meteor shower should rain down its greatest number of meteors on Monday and Tuesday.
Earth intersects Comet Halley’s orbit twice each year. It intersects the comet’s orbit in early May, as the annual Eta Aquariid meteor shower. Then some six months later, in October, Earth in its orbit again intersects the orbital path of Comet Halley as the annual Orionid meteor shower.
Comet 1P/Halley swings into the inner solar system about every 76 years. At such times, the Sun’s heat causes the comet to lose its grip over its mountain-sized mass of ice, dust, and gas, causing the meteor showers.