Skywatch Line for Monday and Tuesday, October 29th and 30th, 2018

This is the Skywatch Line for Monday and Tuesday, October 29th and 30th.

The Sun sets at 5:52 PM; night falls at 7:27. Dawn begins at 5:51 AM and ends with the Sun rising at 7:27.

The parade of bright planets is ending. Jupiter and Mercury, both in Libra, are quite low in the western sky. Jupiter blazes with minus 1.7 magnitude and is about 5º high. Jupiter sets at 6:55 PM. Mercury is less bright at minus 0.2 magnitude, appears about 2º high and is 76% lit. Jupiter helps find Mercury, since it is brightest and 3º directly above the elusive planet. Mercury sets at 6:39 PM. An unobstructed horizon is necessary to observe this pairing.

Saturn, in Sagittarius, shines with zero magnitude, appears about half Jupiter’s size and lies about 21º high in the South, high enough to view its stunning ring system. It sets at 9:15 PM.

Mars, east of Saturn in Capricornus, shines with minus zero magnitude, appears about 86% illuminated and 26º high in the South. The Martian rover Opportunity hasn’t been heard of since the planet-wide dust storm began; NASA still tries to communicate, hoping that seasonal strong winds may blow dust off of its solar panels. Mars is best observed at 7:55 PM and sets at 12:52 AM.

Neptune still resides in Aquarius, glows with 7th magnitude and appears a tiny 2.3 arc-seconds in size. It is best observed at 9:24 PM and sets at 2:59 AM. Uranus, in Aries, rose just before sunset, appears brighter and a bit larger in our telescopes. Uranus is best observed at 12:15 AM and sets at 6:59. Both planets require detailed charts from astronomical media.

The 20-day-old Moon rises in Gemini at 10:05 PM, blazes with minus 10th magnitude and appears 67% lit. Tuesday finds it in Cancer, a bit dimmer and slimmer and rises at 11:09 PM. The Moon sets at 5:47 AM on Tuesday, and after sunrise on Wednesday.

Comet 21P/Giacobini-Zinner still graces the post-midnight sky. It is best seen after 4 AM and before Dawn. The Moon, on both nights, may hinder observations, since it is in the same part of the sky. The comet now is in Canis Major, the Big Dog. It lies about 1º above the Dog’s tail star – ETA Canis Majoris or Aldura. It glows with 9th magnitude, within most amateur telescopes’ ability.

There some objects that are perfect binocular targets.
Directly overhead, the constellation Cygnus seems to fly south for the winter. Below the neck of the Swan is a small constellation – Sagitta. The Latin name means “arrow”, and that is exactly what it looks like. Sagitta is a small constellation; it has a single deep sky object, M71. M71 is a star cluster, but of uncertain type. It displays characteristics of both globular and galactic clusters. It is about 18,000 light years distant, and 30 light-years wide. The binocular observer should see a fuzzy glow about halfway along and a bit below the arrow’s shaft.

Just above the “Arrow’s” tail feathers is a curious object. The Coathanger is an asterism – an image of stars, but not a constellation. This is a perfect binocular target, since a telescope’s magnification destroys the illusion. The Coathanger also goes by the names: Collinder 399 and Brocchi’s Cluster. However, the Coathanger is not a true cluster. Recent Hipparchus satellite measurements show that it is just a random placement of stars that happen to resemble an everyday article.

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