Skywatch Line for Monday and Tuesday, November 19th and 20th, 2018

This is the Skywatch Line for Monday and Tuesday, November 19th and 20th.

The Sun sets at 4:29 PM; night falls at 6:07. Dawn begins at 5:14 AM and ends with the Sun rising at 6:53.

First magnitude planet Mercury hugs the western horizon at Civil Dusk. It glows with first magnitude, appears about 19% illuminated and a medium size of 9 arc-seconds. However, it lies very low and sets at 5:12 PM. Binoculars and an unobstructed view is required.

Saturn, to Mercury’s upper left, inhabits Sagittarius with a zero-magnitude glow and 15 arc-seconds in size. Now is the time for last looks at the giant planet and its famous rings. Saturn sets at 7 PM.

Mars, in Aquarius, shines with minus zero magnitude, appears about 86% lit and about 10 arc-seconds in size. At Civil Dusk, it is about 32º high. It is best observed at 6:19 PM and sets at 11:37.

About 11º East of Mars, Neptune, also in Aquarius, is dimmer at 8th magnitude, a tiny 2.3 arc-seconds in size and 38º high. It is best observed at 7 PM and sets at 12:36 AM. Uranus, in Aries, is brighter at magnitude 5, is larger at about 4 arc-seconds in size and 32º high. It is best observed at 9:49 PM and sets at 4:32 AM. Minor planet 3Juno was closest to Earth on November 16th and was at Opposition on the 17th. This means that it is ideally situated for observation at about Midnight, shining with 7th magnitude. It is located in the dim constellation Eridanus and is closest to the star 35 Eridani. Comet 46P/Wirtanan is traveling through the constellation Fornax and heading toward Eridanus. The comet is predicted to be at 11th magnitude, but could become brighter. Observers of all these objects should consult finder charts, available in various astronomical media.

Monday’s Moon occupies Cetus. The 11-day-old Moon is about 87% lit and blazes with minus 11th magnitude. It is best observed at 9:14 PM and sets at 3:39 AM. Tuesday’s Moon, in Pisces, is a bit brighter and bigger. It is best studied at 10 PM and sets at 4:45 AM. The brilliant Moon lies close to all the above objects, and may hinder detailed observation.

Comet 2018/V1 (Comet Macholz, Fujikawa, Iwamoto) was simultaneously discovered by amateurs. Located in Virgo, it is closest to the star 90 Virginis. The 10th magnitude comet is visible during the hours before Dawn. Again, finder charts are available from various astronomical media.

Venus shares eastern Virgo with the comet and the bright star Spica. Venus dazzles with minus 4th magnitude and a large 48 arc-seconds in size. The planet climbs the sky this month, but shrinks in size. It rises at 4:07 AM and lies about 2º above Spica.

Comets are leftovers from Solar System formation. They reside in the Kuiper Belt, beyond Pluto, and the further Oort Cloud. Comets are mostly ice, with some dirt mixed in. Most stay in those distant regions. However, a comet may receive a gravitational bump and head into the inner Solar System. There are three basic orbits. Some revisit every few years, for example Halley’s Comet; some come too close to the Sun and evaporate away, like 2013’s Comet Ison. A third type arrives and never returns, like the object Omuamua.

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