Skywatch Line for Monday and Tuesday, December 10th and 11th, 2018

This is the Skywatch Line for Monday and Tuesday, December 10th and 11th.

The Sun sets at 4:21 PM; night falls at 6:03. Dawn begins at 5:33 AM and ends with the Sun rising at 7:16.

The waxing Moon, in Sagittarius, dominates the evening sky. At 3-days-old, it shines with minus 5th magnitude, appears about 12% illuminated and is 19º high. It sets at 7:24 PM. Tuesday’s Moon is located in Capricornus, brighter, larger, 24º high and sets at 8:23 PM.

Monday’s Moon shares Sagittarius with Saturn. The Ringed Planet is low at 7º and shines with zero magnitude. Now is the time for last looks, since it sets at 5:48 PM.

Mars shares Aquarius with Neptune. The Red planet shines with zero magnitude, appears about 8 arc-seconds in size, appears about 90% lit and is best observed at 5:46 PM, setting at 11:26 PM. Mars also acts as an aid in locating Neptune, about 2º away. Blue-green Neptune is much dimmer at 8th magnitude and much smaller with 2 arc-seconds in size. Neptune is best studied at 5:38 PM and set at 11:13 PM. Finder charts for Neptune are available from various astronomical media.

Uranus is alone in Pisces, located near the star Omicron Piscium. It shines with 5th magnitude and is larger at 3 arc-seconds in size. It hovers about 57º high at 9 PM and is best observed at 8:24 PM, setting at 3:06 AM.

Comet 46P/Wirtanen is rapidly closing in on Earth. It is closest to the Sun on Wednesday and the Earth on Sunday, about 7 million miles. Recent observers report it about 6th magnitude, near the star 94 Ceti, about 6º below the star Menkar (Alpha Ceti). This is the closest approach by a comet since 1950. These facts imply that it should be visible in amateur telescopes, once the Moon has set.

The comet is also quite near a recently discovered supernova, also in Cetus. It was discovered in late November in M77, a Seyfert galaxy, above the northeast galaxy’s corner, about 7.5º from 94 Ceti. It should be visible in larger telescopes. Again, finder charts for both the comet and supernova are available from various astronomical websites.

Dawn skies present two bright planets. Venus, in Virgo, rises about 3:30 AM, blazes with minus 4th magnitude and appears about 34% lit. Mercury, in Libra, is making a return to Dawn skies, rising at 5:28 AM. The elusive planet blazes with minus zero magnitude and appears about half lit. However, it hovers about a degree above the eastern horizon, making an unobstructed horizon necessary.

Winters in the Northeast are notoriously cloudy. However, when skies are clear, the night sky presents a riot of brilliant stars and constellations that seem close enough to reach out and touch. In fact, twenty-three of the fifty brightest stars are visible in tonight’s sky. Orion, the Dogs and Taurus account for the majority of the brightest stars in the heavens. Sirius is not only brightest on this list, but also second only to the Sun in luminosity; it is also the leading light of Canis Major, the Large Dog. About half of the list lies relatively close to us; the other half is intrinsically brighter, though further away. So, if it is clear, bundle up and enjoy Nature’s sky show.

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