The month of March is named for the planet Mars, which was named after the Roman god of war. March used to be the first month of the year back in the early Roman calendar over 2,500 years ago.

March marks the return of spring for us in the northern hemisphere. This year that will happen a little earlier than usual, at exactly 11:06 p.m. on Tuesday, March 19. This is also known as the vernal equinox. The vernal and autumnal equinoxes are the only two days each year that the sun rises due east and sets due west for everyone on Earth except at the poles. Within a few days of the equinoxes the days are also 12 hours long for everyone on Earth except for the poles.

Notice how the sun will rise a little farther north of east each day during March and set a little farther north of west, thereby tracing out a slightly higher arc each day. March is packed full of such great celestial highlights and next month will be even more dramatic with the long-awaited total solar eclipse passing right over northern Maine, the first one since July 20, 1963. The next one over Maine after the upcoming April 8 eclipse will not be until May 1, 2079, so make sure you plan to see this one! I will write much more about it for my April column.

The planets are evenly split now between the evening and morning sky. Mercury, Jupiter and Uranus will be the evening planets in that order from west to east and Saturn, Venus and Mars will be the morning planets in that order from east to west with Saturn being the lowest on the eastern horizon just before sunrise.

Mercury will make its best evening appearance of the year this month. Our first planet will reach its greatest eastern elongation from the sun of 19 degrees on March 24. It will be visible for more than an hour after sunset, which is about the maximum time because it is always so close to the sun. Venus can rise or set up to three hours after sunset or rise up to three hours before sunrise. Mercury just keeps alternating between being a morning planet and then an evening planet about five times each year.

No spacecraft has ever soft-landed on Mercury and only two of them have ever even orbited it. We have a third one on the way now named Bepi-Columbo that was launched in 2018 and won’t get there until 2025. It takes more energy for a spacecraft to reach Mercury than Pluto, even though Pluto is about 40 times farther away. That is because Mercury is within the powerful and deep gravitational well of the sun. That strong gravity also prevents Mercury and Venus from having any moons.

Mercury’s elliptical orbit traces a continually changing pattern into the sky like a giant spirograph. One day on this little planet with a diameter of only 3,000 miles is equal to 59 earth days. Mercury zips around the sun at 30 miles per second, which is nearly twice as fast as Earth (18.6 miles per second). One year on Mercury is equal to only 88 earth days.

The other evening planets, Jupiter and Uranus are much easier to get to and are also unique and very different from all the other planets in our own solar system and also from the 5,000 or so exoplanets that we have discovered in other solar systems so far.

Jupiter is still in Aries the Ram and is moving in its normal eastward or prograde motion again towards Taurus and the Pleiades. It sets a little earlier each night and we will lose it by the middle of May and then it will show up again in summer as a morning planet. Notice that you can see at least one or two of its four large Galilean moons just with a good pair of binoculars. They are named, Io, Europa, Callisto, and Ganymede. We now know of 95 moons of Jupiter and I am sure we will find even more soon.

Uranus is about 5 degrees to the left, or east of Jupiter, halfway towards the Pleiades open star cluster on the back of Taurus the Bull. It is still close to its best at 5.8 magnitude, but you will need binoculars or a small telescope to see its eerie bluish-green color well. It has 27 moons including five major moons named for characters in some of Shakespeare’s plays. It has rings like all of the gas giants have and it is tilted at 98 degrees, so its equator is nearly at a right angle to its orbit, which takes 84 years. That causes it to have the most extreme seasons of any of our planets.

The rest of the planetary action takes place in our morning sky. Mars rises first about an hour before sunrise, followed by Venus a little later and then Saturn by the middle of March. They are all within about 10 degrees in Aquarius now. Notice that Mars is getting a little higher and brighter each day even while Venus is getting a little lower and fainter each morning.

Comet 12P/Pons-Brooks continues to brighten. It can be seen in binoculars in Pegasus now about 10 degrees below the Andromeda Galaxy. Keep watching as it tracks into Pisces and then Aries. It moves about 1 degree eastward per day. A good photo op will happen for a few days around the equinox when this comet will be just a couple of degrees below the Triangulum spiral galaxy, which is very similar to Andromeda but a little smaller and fainter. It may even become visible without binoculars towards the end of the month and it may get as bright as 4th magnitude although 5th magnitude is more likely. It does not reach its closest approach to the sun until April 21, which is about the time we will lose sight of it here in the northern hemisphere.

The last major highlight this month will be a deep penumbral eclipse of the moon starting at 1 a.m. on Monday, March 25. By 3:13 a.m., 96% of the moon’s disk will be within the earth’s outer shadow, called the penumbra. For it to qualify as a partial lunar eclipse it has to at least partially go into our deeper umbral shadow, which it doesn’t quite do this time. It will end at 5:33 a.m.

Because the moon is only passing into our fainter or penumbral shadow, it will not be very obvious or spectacular, but you should be able to see it pretty well with binoculars or a good telephoto lens. There will be a better partial lunar eclipse visible for us in the eastern U.S. during the next eclipse season on Sept. 18.

MARCH HIGHLIGHTS

March 3: The moon passes only one third of a degree north of Antares in Scorpius this morning. Last quarter moon is at 10:23 a.m.

March 7: The moon passes near Mars this morning. John Herschel was born on this day in 1792. He was a famous astronomer, mathematician and chemist who named seven of the moons of Saturn and four of the moons of Uranus.

March 8: The moon passes near Venus this morning.

March 10: Daylight saving time starts at 2 a.m. New moon is at 5 a.m.

March 13: Percival Lowell was born on this day in 1855. The Lowell observatory in Arizona is named for him. Clyde Tombaugh discovered Pluto there in 1930. On this day in 1781, William Herschel, father of John Herschel, discovered the planet Uranus.

March 14: Albert Einstein was born on this day in 1879. The moon is just below the Pleiades in Taurus today.

March 16: Caroline Herschel, the younger sister of William Herschel, was born on this day in 1750. She discovered seven comets and was the first woman to receive a salary as a scientist.

March 17: First quarter moon is at 12:11 a.m.

March 19: The vernal equinox is at 11:06 p.m.

March 22: Comet Hale-Bopp made its closest approach to Earth on this day in 1997.

March 25: Full moon is at 3 a.m. This is also known as the Worm, Sap, Crow or Lenten moon.

March 30: The moon passes very close to Antares again this morning.

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

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