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.


Mercury, Mars, Jupiter, Saturn, January 2018


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 6th and 7th 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 13th. See a waning crescent moon two days before new next to Mercury on the 15th.


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


Earth is at perihelion (closest to the sun) on the 3rd. 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 23rd. It’s at 0.728 astronomical units from the sun. Mercury is at aphelion on the 25th with a distance of 0.467 astronomical units.


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


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


The moon is at northern lunistice and perihelion on the 1st, perhaps making it seem close, big, and bright to northern hemisphere sky watchers. It’s on the equator going south on the 8th. When the moon is new on the 15th, it’s also at southern lunistice and apogee. It comes north of the equator again on the 23rd. Northern lunistice is on the 29th. 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 5th, Mars and Jupiter 0.2° on the 7th, Venus in superior conjunction on the 8th, Jupiter and the moon 4.2° on the 11th, Mars and the moon 4.4° also on the 11th, Mercury and Saturn 0.6° on the 13th, Saturn and the moon 2.6° on the 15th, Mercury and the moon 3.4° on the 15th, Venus and the moon 2.5° on the 17th, Neptune and the moon 1.5° on the 20th, Uranus and the moon 4.4° on the 24th, and the moon and Aldebaran 0.7° on the 27th.


The Quadrantids meteor shower peaks on the 3rd and 4th. 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.

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