The month of January is named after the Roman god, Janus. He is the god of transitions, gates, doors, endings and beginnings, and time itself. He is depicted with two faces ”“ always facing forwards and backwards at the same time. That is a good way to enter any new year, remembering what we learned in the past, and always looking forward to the future to learn more about where we really are.

The days are already getting longer now that we are past the winter solstice. Long nights are great for people interested in what is always going on in the skies above them. There are several good conjunctions and other unique events this first month of the new year that will be worth making an effort to see, even if it gets icy cold.

Jupiter will be rising a little earlier each evening, approaching its opposition early next month. Venus and Mercury will be quite close to each other, low in the evening sky, a half-hour after sunset with Mars just above this celestial duo of our first two inner planets. Saturn has switched to the morning sky and it will pass just two degrees ”“ or about two fingers at arm’s length ”“ below the waning crescent moon one hour before sunrise on Friday, Jan. 16. Earth will be closest to the sun on the fourth day of this month. As a bonus, there will also be a comet named Lovejoy visible with a small telescope, an asteroid named Juno, and a meteor shower named the Quadrantids.

Jupiter begins the month rising around 8 p.m. in the constellation of Cancer, just to the west of Leo, and will end the month rising by 6 p.m. The king of the planets is getting slightly closer and brighter each night as it approaches its opposition on Feb. 6, when the Earth will be directly between Jupiter and the sun. Our largest planet will only be 400 million miles away ”“ or about 36 minutes at the speed of light. That will be its best opposition until 2019. Its average distance is 484 million miles, or 43 minutes at the speed of light. Jupiter reaches opposition every 13 months. The moon does this every month when it reaches full moon.

Venus and Mercury will be nicely visible within just 5 degrees of each other for the first three weeks this year. Look low in the southwestern sky about a half-hour after sunset each clear evening this month to watch this celestial dance unfold. Notice that orange Mars is only about 15 degrees to the upper left of this dynamic duo.

These two planets are called inferior planets because they are located closer to the sun than the Earth. They are the only planets in our solar system with no moons and the only ones that go through phases like our moon, but on a different rhythm. They also have very long days and very short years since they spin very slowly. A day on Mercury lasts 59 days, and a year lasts only 88 days. A year on Venus lasts 225 days, and its days last 243 days.

There are also many things about these first two planets that are very different and even opposite from one another. Venus has the highest surface air pressure of any place in our whole solar system. It is about 100 times that of Earth’s surface, or the same pressure as if you were 3,000 feet under our ocean. Mercury has no air at all.

Venus is the most reflective planet, and Mercury is the darkest, only as reflective as an asphalt parking lot. Venus has the most circular orbit and Mercury the most eccentric, or oval orbit. It slows down and speeds up all the time and you could even see the huge sun rise, and then drop below the horizon, and then rise again the same day from the surface of Mercury. Venus is tilted 177 degrees on its axis, almost upside down. Mercury has almost no tilt at all, only one-30th of a degree. That means the plane of its equator is its path around the sun. Mercury has a perfect 3-2 resonance, making three spins on its axis for every two times it orbits the sun.

Venus is always the same temperature of 870 degrees ”“ hot enough to melt some metals and hot enough to cook a pot roast in two seconds. Mercury has the largest range of temperatures of any place in our solar system. It plunges 1,000 degrees after sunset each day. It is hot enough to melt lead in the daytime and cold enough to liquefy oxygen at night. The strangest thing is that Venus is brightest when it is closest to Earth, which you would expect, but Mercury is brightest when it is farthest away from Earth. So Mercury can change its brightness by a factor of more than 1,000.

Saturn is now visible in the morning sky in the constellation of Scorpius, near Antares where Mars was in October of last year. A slender, waning crescent moon will be two degrees to the left of the ringed planet on the morning of Jan. 16.

Comet Lovejoy will be visible in a small telescope at around 8th magnitude, cutting a nice path just to the right of the famous winter hexagon all this month. It will begin the month just to the right of Rigel, the blue giant star in Orion, continue through Taurus just to the right of the Pleiades, and travel all the way to Andromeda this month. It is moving quite fast now, covering 3 degrees of the sky each day. It will be at its closest approach to Earth at 44 million miles in early January. Discovered by Terry Lovejoy on Aug. 17, 2014 from Brisbane, Australia, this is already the fifth comet that this amateur astronomer has had named in his honor, for being the first person on Earth to spot these celestial visitors.

The asteroid named Juno will reach opposition on Jan. 29 in the constellation of Hydra below the Winter Hexagon. It will be around 8th magnitude, similar to Comet Lovejoy and not too far from it in the sky to begin the month. This was the third asteroid discovered, back in 1804, just three years after the first and largest asteroid, Ceres, was discovered. Ceres, at 600 miles in diameter, is about the size of Texas. Then, there is Vesta at 330 miles, Pallas at 320 miles, and Juno at 170 miles in diameter. These four largest asteroids make up about half the mass of all the millions of asteroids in the belt between Mars and Jupiter.

The Quadrantid meteor shower peaks on Saturday, Jan. 3 into Sunday morning, Jan. 4. This shower could produce more than 100 meteors per hour, but this year, the moon will be nearly full, so you would be lucky to see about a dozen or so per hour, toward morning when the moon is sinking low into the west. Named after a defunct constellation Quadrans Muralis, these meteors will originate from a point in the sky near the Big Dipper and Draco the dragon.

Jan. 1: On this day in 1801 Giuseppe Piazzi discovered the largest of all asteroids, Ceres.

Jan. 3: The Quadrantid meteor shower peaks.

Jan. 4: Earth is at perihelion, or closest to the sun today at 91.4 million miles, or about 3 percent closer to the sun than it is at aphelion in July. Full moon is at 11:53 a.m. EST. This is also called the Wolf Moon or the Moon after Yule.

Jan. 7: On this day in 1610 Galileo discovered 3 of the 4 largest moons of Jupiter. They are Callisto, Europa, and Io. He would discover the largest moon in the whole solar system, Ganymede, at 3200 miles in diameter, just 6 days later.

Jan. 8: The moon passes 5 degrees south of Jupiter this morning.

Jan. 13: Last quarter moon is at 4:46 a.m.

Jan. 14: Mercury is at greatest eastern elongation from the sun at 19 degrees today. On this day in 2005 the Huygens probe landed on Titan, the largest moon of Saturn and the only moon with an atmosphere.

Jan. 19: The New Horizons mission to Pluto was launched on this day in 2006. It will not get to Pluto until July of this year, but it will already begin to be able to take better pictures of this icy dwarf than the Hubble Space Telescope ever could within a few months. The spacecraft was reawakened last month from its long hibernation and is healthy and ready to discover new truths about Pluto that could go well beyond our imagination of what is possible.

Jan. 20: New moon is at 8:14 a.m.

Jan. 21: The slender, waxing crescent moon passes close to Venus and Mercury this evening.

Jan. 23: The first 3 moons of Jupiter that Galileo discovered will have their shadows transit Jupiter over an 8-hour period tonight.

Jan. 26: First quarter moon is at 11:48 p.m.

— Bernie Reim is an amateur astronomer and teaches at the University of Southern Maine.

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