Mars, Jupiter, Saturn take center stage in sky January’s full Moon After Yule shines on the 28th

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January is named for Janus, the two-faced Roman god who could see both the past and the future. Ovid wrote that Janus was the keeper of the gates of heaven and the custodian of the universe – all in all, an appropriate choice to start a new year of stargazing!

Focus on the planets

Mercury may be found low in the southwest at twilight for the first half of the month. On Jan. 14, Mercury lies directly above the nearly new moon about a half-hour after sunset.

Venus is lost to view as it undergoes superior conjunction with the sun and will not reappear until spring when it enters the evening sky.

Mars is prominent in the southwest during the early evening hours. Look for the Red Planet on the 18th of the month when it is situated to the upper right of the crescent moon. Far below Mars lies the solitary star Fomalhaut.

Jupiter is well up on the eastern horizon at sunset. The giant planet is the brightest object, other than the moon, in the sky and remains in view nearly all night.

Saturn is above, and to the right of Jupiter as the skies darken. The tilt of Saturn’s rings is extremely favorable for telescopic viewing. On the night of Jan. 24, the moon, Saturn and Aldebaran form a tight grouping.

The Pleiades star cluster is to Saturn’s upper right. Uranus, Neptune and Pluto are all lost to view in January.

Our celestial neighbors

The last, and also the least, planet in the solar system is tiny Pluto having a radius only two-tenths that of the Earth. Indeed, many astronomers once lobbied to remove Pluto from the hierarchy of planets, saying it most likely was a runaway satellite of Neptune. That theory lost support in 1978 when Pluto’s satellite, Charon, was discovered.

Pluto is 40 times farther from the sun than Earth and it takes 249 Earth years for it to make one orbit of the sun. This means that the last time Pluto was at its current point in its “year,” the Revolutionary War had yet to take place. Pluto was discovered in 1930 by Clyde Tombaugh using a tedious process that compares two pictures of the same area of the sky taken several hours apart. A rapid flipping back and forth between the two pictures would show the stars staying fixed in position but Pluto showing up as a tiny streak. Pictures taken by the Hubble Space Telescope have shed some light on Pluto’s nature but it still remains one of the mysteries of the solar system.

January events

1 Sunrise, 7:13 a.m.; sunset, 4:05 p.m.

2 The Earth is at perihelion, or closest approach to the sun, for the year.

The Earth is 3.3 percent closer to the sun than at aphelion in July. Then why is it so much colder now than in July? The moon is at perigee, or closest approach to Earth, for the month.

3 This is the peak night for the Quadrantid meteor shower. However, it will be all but completely washed out by moonlight.

6 Moon in last quarter, 10:56 p.m.

10 If you are up and about an hour before sunrise, look to the southeast for a thin crescent moon to the immediate left of orange Antares.

13 New moon, 8:30 a.m.

14 Mercury lies almost directly above the nearly new moon an hour after sunset.

18 Mars is to the moon’s upper right about 45 minutes after sunset. The moon is at apogee, or farthest distance from the Earth, tonight.

19 The sun enters Capricornus on the ecliptic.

20 The sun enters the astrological sign of Aquarius even though it has just entered Capricornus astronomically.

21 Moon in first quarter, 12:48 a.m.

24 Tonight finds the moon, Aldebaran and Saturn in a tight grouping with the Pleiades to the upper right.

27 Castor and Pollux, the twin stars of Gemini, are to the moon’s immediate upper left this evening.

28 Full moon, 5:51 p.m. The full moon of January is called the Old Moon or the Moon After Yule.

30 The moon is at perigee for the second time in January.

31 Sunrise, 6:56 a.m.; sunset, 4:42 p.m.

Clair Wood taught physics and chemistry for more than a decade at Eastern Maine Technical College in Bangor.