Skywatch Line for Monday, and Tuesday, January 13th and 14th, 2020

This is the Skywatch Line for Monday, and Tuesday, January 13th and 14th, written by Joe Slomka.

The Sun sets at 4:44 PM; night falls at 6:24. Dawn begins at 5:44 AM and ends with the Sun rising at 7:24.

The Moon occupies Leo on both nights. Monday’s Moon rises at 8:15 PM appears about 87% illuminated and sets at 10:12 AM, Tuesday. Tuesday’s Moon rises at 9:30 PM, is 79% lit and sets at 10:42 AM, Wednesday. Monday’s Moon is at perigee (closest to Earth), which means it is about 227, 396 miles away; it is also quite close to Leo’s brightest star, Regulus.

Venus is the only bright planet during evening. In Aquarius, it blazes with minus 4th magnitude and appears about 14 arc-seconds in size. This month Venus gains altitude from about 27° to 34° at month’s end; it sets at 7:45 PM.

Nightfall brings out Neptune and Uranus. Neptune, also in Aquarius, glows with 8th magnitude, appears a tiny 2 arc-seconds in size, is moderately high in the West and sets at 9:11 PM. Uranus, still occupying Aries, shines with 6th magnitude, about 4 arc-seconds big and sets at 1:13 AM. Finder charts for these planets are available from astronomy magazines and websites.

Mars is the only visible Dawn planet. It rises about 3 hours before the Sun at 4:09 AM, shining with 1st magnitude, growing to about 4 arc-seconds and sets at 1:20 PM. Mercury is in the sky, but too close to the brilliant just risen Sun.

Planets are considered to be in Superior Conjunction when they pass behind the Sun, from Earth’s view. Monday, Saturn makes a rare trip behind the Sun, followed by Pluto, two hours later. Of course, both are hidden by our Sun and will become visible later this year.

As the Sun sets, the giant constellation Orion appears. Canis Major, the Big Dog, follows at Orion’s heels. Sirius, the Dog Star, is among the closest stars to our Solar System, at 8.6 light-years. Although stars seem fixed in our sky, they are actually traveling in different directions and speeds. Sirius is one of these. In sixty thousand years, it will approach to 7.8 light-years and increase its brightness only marginally. Sirius is not a solitary star; it has a companion, appropriately nicknamed “The Pup.” This star closely orbits Sirius once every fifty years. This star is much smaller and dimmer than the primary. Sirius B, as this star is formally called, is still a bit too close. In a few years, amateur telescopes may spot The Pup, once Sirius’ brilliance is blocked. Sirius B is about the Earth’s size, but has the Sun’s mass.

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