Although no meteor shower, eclipse or bright comet will liven up the March sky, you can still look forward to some surprises. The ballet of the planets this month offers some unexpected observations and stimulating challenges.
Inner planets pull a switcheroo
Usually, Venus is dazzlingly bright, attracting anyone out for an evening walk, whereas special conditions are needed for you to spot Mercury. This month, however, the two inner planets have some surprises in store. Mercury will be easier to make out, while Venus will be more of a challenge around the third week of March.
During the second half of the month, the shy planet Mercury enters its best observation period for the year. You can see its faint coppery glow at twilight, 30 to 45 minutes after sunset. It can be observed only above a perfectly clear west-northwest horizon, and binoculars can help you spot it more easily. The third week of March is the best time because the planet will be slightly brighter then.
To find the smallest planet in the solar system, you can count on a nearby celestial body to guide your eye. On the 18th, Mercury will lie 8.5 degrees to the left of brilliant Venus. On the 29th, a thin crescent Moon will be found 10 degrees to its left, and Mars, located above the two, will form a large triangle with them.
Venus poses a real challenge
Since the start of the year, Venus has shone as the Evening Star. But as of early March, it’ll drop toward the Sun at an ever-faster rate, and by late March, it’ll have become the Morning Star and remain so till late summer. If you want to set yourself a real challenge, you can try to observe Venus in the evening and morning of the same night.
Since the planet is at its inferior conjunction on the 25th far to the north of the Sun (at over eight degrees), it’s possible to make out Venus glimmering in the twilight low on the west-northwest horizon just after sunset and to spot it coming up the next morning just before sunrise in equally tricky conditions in the east-northeast. The best period to attempt this feat is a two- to three-day window around the 22nd. The phenomenon occurs very low on the horizon, and its observation requires some preparation.
Mars at a standstill
This month, Mars appears to be at a standstill as it revolves around the Sun. The planet moves eastward along the ecliptic at about the same pace as the constellations in which Mars is moving shift toward the western horizon. A keen observer looking westward at the same hour each evening will therefore be surprised to see Mars roughly in the same place throughout the month.
Although the red planet is much less bright than at its opposition, you can spot it easily among the faint stars of the constellations Pisces (the first week of the month) and Aries (as of the 8th). It’s the only dot of red light not twinkling in this part of the sky. One hour after sunset, you can easily observe Mars due west about 20 degrees above the horizon. The red planet sets just before 9:30 EST. The Moon can help you find it on the 1st when a thin crescent lies 4.5 degrees to its left, as well as on the 30th when the two bodies are seven degrees apart.
Zodiacal light, a gift from the equinox
Every year, the two weeks around the spring equinox (on March 20 at 6:28 EDT this year) are ideal for observing the zodiacal light. Sunlight reflecting off dust between the planets along the plane of the solar system can be seen more easily during this period when the angle between the western horizon and the ecliptic is quite steep. The zodiacal light appears as a white glow shaped like a long triangle or pillar and stands out in a sky free of light pollution. It can be seen in the evening, about one hour after sunset, above a clear western horizon. Observing the phenomenon can be tricky, but another good time to try your luck is at dawn close to the fall equinox.
Remember that we move to daylight saving time on the night between March 11 and 12. Until next November, our clocks will be one hour ahead of the Sun.