January 2018

The new month and the new year start with a full moon. The moon will be full again at month’s end. By some definitions, that is a blue moon. And by those definitions, there will be a second blue moon in 2018, as March also has a full moon at its beginning and end.

 

 

None of the naked eye planets are visible at sunset at the start of January. Aquila is setting, Pegasus is high, and Orion is rising. Gemini rises in mid-evening. Leo is a late evening riser. Find Mars and Jupiter rising with Libra in the morning. Mercury rises closer to dawn with best viewing from the equator. Saturn also rises close to dawn but is very hard to find in the sun glow. The best bet would also be from places at or near the equator. You won’t see Venus. It’s on the other side of the sun.

 

Pay attention to Mars and Jupiter. Jupiter is entering the diamond of Libra. Mars is following it. They’ll be very close together around the 6^th and 7^th with just 0.2° between them. Mars will keep moving eastward out of the diamond and leaving Jupiter behind.

 

The year and month also start with Mercury at greatest elongation. It’s 22.7° west of the sun. The planet is approaching Saturn in the morning sky and passes it on the 13^th. See a waning crescent moon two days before new next to Mercury on the 15^th.

 

Venus goes around the sun on the other side coming through superior conjunction on the 8^th. It barely emerges in the evening sky by the end of the month.

 

Earth is at perihelion (closest to the sun) on the 3^rd. It’s at 98.3% of its average distance from the sun. The average earth-sun distance is called an astronomical unit. Venus is at aphelion (farthest from the sun) on the 23^rd. It’s at 0.728 astronomical units from the sun. Mercury is at aphelion on the 25^th with a distance of 0.467 astronomical units.

 

The moon occults Regulus on the 5^th. The visibility area is Alaska, northern Canada, Greenland, and the Arctic Ocean. The moon passes in front of the asteroid Vesta on the 12^th. Viewers with dark enough skies in South Africa will get to see it. And Aldebaran is occulted on the 27^th for viewers in northeast Asia, northwest North America, and the Arctic Ocean.

 

Lunar phases this month are: full on the 2^nd, last quarter on the 8^th, new on the 17^th, first quarter on the 24^th, and full again on the 31^st.

 

The moon is at northern lunistice and perihelion on the 1^st, perhaps making it seem close, big, and bright to northern hemisphere sky watchers. It’s on the equator going south on the 8^th. When the moon is new on the 15^th, it’s also at southern lunistice and apogee. It comes north of the equator again on the 23^rd. Northern lunistice is on the 29^th. That’s the day before another perigee. So the second full moon of the month is likely to seem big, bright, and close too.

 

Conjunctions of note this month: The moon and Regulus 0.9° apart on the 5^th, Mars and Jupiter 0.2° on the 7^th, Venus in superior conjunction on the 8^th, Jupiter and the moon 4.2° on the 11^th, Mars and the moon 4.4° also on the 11^th, Mercury and Saturn 0.6° on the 13^th, Saturn and the moon 2.6° on the 15^th, Mercury and the moon 3.4° on the 15^th, Venus and the moon 2.5° on the 17^th, Neptune and the moon 1.5° on the 20^th, Uranus and the moon 4.4° on the 24^th, and the moon and Aldebaran 0.7° on the 27^th.

 

The Quadrantids meteor shower peaks on the 3^rd and 4^th. However, due to the moon being just past full, don’t expect to see any but the brightest meteors. The radiant point for this shower is between Boötes and Draco in a part of the sky once referred to as the Quadrant. The radiant point rises around midnight, so most of the shower would be visible in the morning hours. And it’s fairly far north, so southern hemisphere viewers are mostly left out of this shower.