January is named for the Roman god Janus, who faces both forward and backward at the same time. He is the god of beginnings and transitions. As we enter this new year, we can reflect on some of the great discoveries in astronomy that happened last year and look forward to many more great discoveries as we keep searching and expanding our knowledge.

The top five discoveries last year:

SKY GUIDE: This chart represents the sky over Maine during January. The stars are shown as they appear at 9:30 p.m. early in the month, at 8:30 p.m. at midmonth and at 7:30 p.m. at month's end. Mars is shown in its midmonth position. To use the map, hold it vertically and turn it so the direction you are facing is at the bottom. Sky chart prepared by George Ayers

1) Two gravitational waves were confirmed using LIGO, the Laser Interferometer Gravitational-wave Observatory. This amazing phenomenon was first predicted by Albert Einstein over 100 years ago, and has just now been found and proven. These are ripples in the fourth-dimensional fabric of space-time in which everything is embedded. Those two particular waves were caused by mergers of 30 to 40 solar mass black holes just over a billion light years away. That detector can only hear such waves of higher frequency, but many gravitational waves of all frequencies are passing through the earth all the time. This opens a whole new window on astronomy since it goes way beyond any of the wide range of electromagnetic telescopes from gamma ray to radio that we now use to gain most of our knowledge.

2) An earth-like planet was discovered right next door, orbiting the closest star, Proxima Centauri, only 4.2 light years away. We now have evidence that there may be about as many planets just in our own galaxy as there are stars, around 300 billion. About every 10th star may have 10 or so planets. We have found over 2,000 new exoplanets over the past few years, but only a handful that could have the right conditions for liquid water, which is probably extremely rare elsewhere in the universe.

3) Rockets made by SpaceX and Blue Origin proved several times last year that they can reuse their main boosters by executing perfect vertical landings under power. This will make space travel much less expensive, so more of it will happen and more satellites will be launched.

4) More of Pluto and the Kuiper Belt are being revealed. New Horizons flew very close to Pluto on July 14, 2015, but important new data is still coming in and it will now also fly very close by 20 to 25 more Kuiper Belt objects. The next one will happen on Jan. 1, 2019. They found that Pluto has been active just the past several million years and they discovered a thicker atmosphere than expected.

5) Juno successfully arrived at Jupiter on July 4 and is making extremely elongated 53-day orbits plunging in over the poles and quickly getting far away to avoid the dangerous high-energy particles generated by Jupiter’s strong magnetic fields. Juno’s computer and sensitive instruments are shielded by sitting inside a 400-pound vault of titanium. This mission should relay important data back to us until February 2018.

Highlights for this first month of 2017 include Venus climbing higher into the evening sky near its best and brightest for the year, a conjunction of Mars and Venus, Saturn returning to our morning sky, Mercury near its best for the year in the morning sky, a bright asteroid in Cancer and Gemini, a fairly bright comet in Capricorn and a good meteor shower on Jan. 3.

Venus is now putting on its best evening apparition in five years. It will reach its greatest eastern elongation from the sun on the 12th but won’t reach its brightest until early next month.

Venus will be half lit at this point. But it takes Venus 225 days to make one orbit around the sun and it only takes the moon 29 days. Venus will reach 30 degrees above the western horizon an hour after sunset and it won’t set until 9 p.m.

Then we will travel about 10 degrees east of Venus in Aquarius and see Mars. It’s now just over 100 times fainter than Venus but is still distinctly orange and brighter than any star close to it. Neptune is also nearby but another 630 times fainter than Mars and you would need a telescope to spot it at nearly 3 billion miles away. Pluto, an icy dwarf, is about 4.5 billion miles from Earth.

Saturn returns to our morning sky this month. It can be seen just above and to the right of Mercury low in the southeastern morning sky about a half-hour before sunrise.

This year’s brightest asteroid, Vesta, can be seen with binoculars moving westward from Cancer into Gemini this month, rising around sunset.

Comet 45P/Honda-Mrkos-Pajdusakova should reach 7th magnitude in the evening sky this month. Watch as it traces a nice loop through the constellation of Capricorn. It returns every five years and this will be one of its best appearances since it was discovered in 1948. There should be four more comets reaching 7th magnitude or brighter in the next half year.

The Quadrantid meteor shower peaks Jan. 3. There will be ideal conditions since the waxing crescent moon will have set by 10 p.m. We can expect up to 120 meteors per hour if it is clear, all originating from a point in the sky near the Big Dipper.

JANUARY HIGHLIGHTS

Jan. 1: On this day in 1801, Giuseppe Piazzi discovered the first asteroid, Ceres. At 600 miles in diameter, it is the largest of all of the millions of asteroids that orbit in a belt between Mars and Jupiter. Vesta is the second- largest at about 300 miles across, or about the width of Arizona.

Jan. 2: A slender waxing crescent moon passes within 2 degrees of Venus and Mars this evening. Look for the ghostly glow of earthshine reflecting off the darker part of the moon.

Jan. 3: The Quadrantid meteor shower peaks this morning. One of only two major meteor showers caused by asteroids and not comets, this shower is caused as we pass through debris from an asteroid named 2003 EH1, which could be an extinct comet nucleus.

Jan. 4: Earth is at perihelion, or closest to the sun, at 91.4 million miles away this morning.

Jan. 5: First-quarter moon is at 2:47 p.m.

Jan. 7: On this day in 1610, Galileo discovered Callisto, Europa and Io, three large moons of Jupiter. He would discover Ganymede, the biggest moon in our solar system, just six days later.

Jan. 8: Stephen Hawking was born on this day in 1942.

Jan. 12: Full moon is at 6:34 a.m. This is also known as the Wolf Moon or Old Moon.

Jan. 14: On this day in 2005 the Huygens probe landed on Titan, the largest moon of Saturn.

Jan. 17: The asteroid Vesta is at opposition tonight. That means it rises at sunset and doesn’t set until sunrise, and is at its best and closest for the year.

Jan. 19: Mercury reaches its greatest eastern elongation from the sun. Last-quarter moon is at 5:13 p.m. The New Horizons mission to Pluto was launched on this day in 2006. It got there on July 14, 2015.

Jan. 24: The moon passes near Saturn this morning and Mercury the next morning.

Jan. 27: New moon is at 7:07 p.m.

Bernie Reim of Wells is co-director of the Astronomical Society of Northern New England.

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