March was the first month of the year on the early Roman calendar. It is named after Mars, the Roman god of war. March always marks the start of spring in the northern hemisphere. That will happen Tuesday, March 20 at 1:14 a.m.

The vernal equinox and autumnal equinox are the only two days each year the sun rises due east and sets due west except at the poles. The equinoxes are also the only two days that the days and nights are both 12 hours long, but that happens a few days before the equinoxes due to our elliptical orbit.

The saying “March comes in like a lion but goes out like a lamb” could refer to the weather, but it could also refer to Aries the Ram setting in the west as Leo the Lion approaches the zenith. This year most of the winter has been like a lamb, so we will see what March brings.

This March we will witness a dramatic dance of planets. All five of our brightest planets will be visible at some point in our evening sky, but only four at the same time because Mercury will set before Saturn rises.

On the first three evenings in March, the six brightest objects in the night sky will be visible 45 minutes after sunset. These are the moon, then Mercury, Venus and Jupiter in the west, Mars in the east and Sirius, the brightest star in the sky, in the southeast.

Watch carefully as Venus continues to close in on Jupiter for the first half of March. As the month begins, Venus is still 11 degrees below and to the right of Jupiter, with Mercury another 20 degrees below Venus. Closing at the noticeable rate of one degree per day, Venus will finally catch up with the king of the planets on March 12, just 3 degrees to the right of Jupiter. That distance can be measured in the sky by holding up two fingers at arm’s length.

Brilliant Venus will be 2 magnitudes, or just over 6 times brighter than Jupiter. This brilliant pair will not set until almost four hours after the sun.

Through a telescope you will see Venus is now down to about 60 percent illuminated by the sun. It will reach exactly half lit, which is also called greatest elongation, on March 27. It will look like a first quarter moon but about 60 times smaller.

We had an even more dramatic planetary lineup just under 10 years ago, in April and May 2002. All five of the brightest planets were visible within less than half the sky just after sunset in the evening sky.

I well remember doing some astronomy shows on a little mountain in Acton for fifth-graders and enjoying that rare sight with them above the backdrop of some great scenery, including lakes and mountains with the new light green leaves of spring just beginning to transform our landscape. The last good lineup before that was back in 1940.

As if having all those planets in our evening sky this month was not thrilling enough, Mars will reach opposition on Saturday. That only happens every 26 months. Mars is only really bright and impressive for a little over one month out of those 26 months. That is when you can see nice features on Mars like dark markings and ice caps, even through a small telescope.

Mars will rise at sunset and not set until sunrise. It will reach its highest point in the sky at midnight on the third. This will not be a close opposition because it will be just past its farthest point from the sun. Mars will be 63 million miles from Earth on this opposition. By comparison, on its famous Aug. 27, 2003, opposition, which was its closest one in nearly 60,000 years, Mars was only just under 35 million miles away. The last people that ever saw Mars any closer were the neanderthals, and they probably had no idea what they were really seeing. It got as bright as minus 2.9 magnitude, which is over three times as bright as our brightest star, Sirius. It also reached a size of 25 arc seconds, or only about 60 times smaller than the full moon. This time Mars will only reach a size of just under 14 arc seconds in diameter, and a brightness of only minus 1.2 magnitude, or not even as bright as Sirius.

Saturn begins the month rising four hours after sunset but will end the month rising only one hour after sunset, approaching its own opposition on April 13. Saturn is in retrograde, or westward motion now, heading toward the bright star Spica in Virgo. Mars is also in retrograde, heading toward Regulus, the brightest star in Leo the lion.

Along with the opposition, the great lineup of planets, and the nice conjunction of Venus and Jupiter, we will also get to see the consistent Comet Garradd. It passed through Hercules and Draco the Dragon in February and will be in Ursa Minor and Ursa Major in March. That means it will be up all night instead of rising around 2 a.m. like part of February. It should be around 7th magnitude, which means you will need binoculars to see it. Through a telescope you should be able to see that it has a short blue gas tail and a whiter dust tail.

March highlights

March 3. Mars reaches opposition in Leo tonight.

March 6. The nearly full moon is just to the right of Regulus in Leo tonight one hour after sunset. On this day in 1986, Vega 1 made its closest approach to Halley’s comet. This was an unmanned Russian spacecraft in cooperation with several European countries that also flew by Venus. A second Vega mission flew by Halley’s comet three days later.

March 7. A nearly full moon is just to the right of Mars about 45 minutes after sunset.

March 10. The moon forms a nice triangle with Saturn and Spica by 10 tonight.

March 12. Venus and Jupiter are just 3 degrees apart in the western evening sky 45 minutes after sunset. Look for Mercury another 30 degrees below the pair. On this day in 1981, a Russian cosmonaut became the 100th person in space. Now, over 30 years later, about 500 people have been in space. That is only a tiny percentage of the seven billion people currently sharing Spaceship Earth.

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