Skywatch Line for Monday and Tuesday, December 31st, 2018 and January 1st, 2019

This is the Skywatch Line for Monday and Tuesday, December 31st and New Year’s Day (January 1st).

The Sun sets at 4:31 PM; night falls at 6:13. Dawn breaks at 5:44 AM and ends with the Sun rising at 6:54 AM.

Mars is the only bright planet visible from Dusk to Midnight. Mars lies sandwiched between Neptune and Uranus. Neptune, in Aquarius, lies about 15º below Mars and flickers with minus 8th magnitude and only 2 arc-seconds in size. Neptune sets at 9:52 PM. Mars, in Pisces, shines with zero magnitude, shrinks to 7 arc-seconds in size and appears about 87% lit. The Red Planet is best observed at 5:14 PM and sets at 9:21. Uranus shares Pisces with Mars. It glows with 5th magnitude and appears about 6 arc-seconds in size. It is best observed at 7:01 PM and sets at 1:42 AM. Both Uranus and Neptune require finder charts from various astronomical media.

Comet 46P/Wirtanen resides in the dim constellation Lynx. It is fading to 10th magnitude as it retreats from Earth. Again, finder charts will assist the observer.

Dawn brings the arrival of brilliant planets and the Moon. The Moon occupies Libra on both nights. It appears about 19% lit on Tuesday morning and 12% on Wednesday; it dims from minus 7th magnitude on Tuesday to minus 6th magnitude, Wednesday.

Venus shares Libra with the Moon, appearing about 47% illuminated and shining with minus 4th magnitude, having risen at 3:37 AM. Jupiter, rising at 5:16 AM, lies about 18º below Venus in Ophiuchus, glares with minus 2nd magnitude and appears about 32 arc-seconds in size. Mercury, also in Ophiuchus, rises about 6:18 AM, appears about 90% lit and blazes with minus zero magnitude. Jupiter may be too low for useful observations, and Mercury needs an unobstructed horizon to be seen.

Monday night will find most people watching a manmade star fall in Times Square. Astronomers will be watching something else at the same time. The New Horizons spacecraft, having flown past Pluto, will fly by another, even more distant member of our Solar System, asteroid 2014MU69, nicknamed Ultima Thule. This is the furthest heavenly body studied. Ultima Thule is about 20 miles in diameter. New Horizons will zoom by, taking pictures and measurements, three times closer than when it visited Pluto. NASA plans live coverage starting 12:15 AM, Tuesday on various NASA channels, like NASA TV, NASA.gov, etc. However, if the government shutdown continues, you can watch the flyby on the Johns Hopkins Applied Physics Laboratory You Tube channel.

Tuesday is, of course, New Year’s Day. Other cultures celebrate different days. For some, it is the Spring Equinox, others the Winter Solstice. Ancient Egyptians marked the rising of the star Sirius. Chinese celebrate New Year’s between January 20th and February 20th due to a lunar calendar. New Year’s Day also varies in the lunar Islamic calendar. Western calendars begin on January First – thanks to Julius Caesar. The Roman calendar was a mess; it contained 354 days. Extra months had to be inserted to keep in step with the Sun. While Caesar courted Cleopatra, he met her astronomer, Sosigenes, who recommended calendar reform. Caesar adopted those suggestions. On January First 45 BC, the new calendar became effective. It called for 365 days and twelve months. A leap day would be added every four years, to keep the calendar in sync with the Sun. With minor changes, this is the calendar we now use.

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