In the evening sky in March, Mars begins near the Pleiades, or Seven Sisters, star cluster—a feast for binoculars—and moves slowly eastward against the attractive background of Taurus the Bull. In the morning sky, Jupiter and Mercury form a close pair low in the east-southeast early in the month, with Saturn not far to their upper right.
Evenings: In evening mid-twilight, as March opens, the brightest objects are Sirius, the Dog Star, in the south-southeast, and Capella, the Mother Goat star, 12 degrees north of overhead. These stars mark the southern and northern apices of the huge Winter Hexagon. In clockwise order from Sirius, find Procyon, Pollux/Castor, Capella, Aldebaran, Rigel and back to Sirius.
Mars, fading from magnitude +0.9 to +1.3 in March, is high in the west-southwest to west, and moving eastward about 0.6 degrees per day against a truly attractive star background. Look nightly March 1-6, and watch Mars pass within 3 degrees south of the Pleiades star cluster. The view through binoculars will be wonderful! On March 15 and 16, Mars will be about midway between the Pleiades and Aldebaran, the first-magnitude star marking one eye of Taurus, the Bull. During March 19-21, Mars passes within 7 degrees north of Aldebaran. Compare the brightness and color of the two objects. Aim binoculars at Aldebaran, and within the same field of view, you’ll see many fainter stars which are members of another star cluster, the Hyades. The brighter stars of the Hyades form a “V” with the foreground, non-member star Aldebaran. Together, the Hyades and Aldebaran form the head of Taurus.
In 2021, Mars takes about 60 days to cross Taurus, from late February until late April. Next time around, Mars will take 7 1/2 months to cross this constellation, from early August 2022 until late March 2023. That passage will include Mars retrograding—moving backward—from Oct. 30, 2022 to Jan. 12, 2023. Near the middle of its retrograde, on Dec. 7, 2022, Mars will be at opposition and will shine at magnitude -1.8, brighter than Sirius!
The moon makes a pass through the early evening sky on March 14-28, while changing from a thin crescent to full. Moving an average of 13 degrees per day against the background of the zodiac constellations, the waxing moon moves through Pisces; Aries; Taurus(including the Pleiades, Aldebaran, and Mars); Gemini(including Pollux and Castor); Cancer; Leo (including Regulus); and Virgo (including Spica, not yet risen at mid-twilight in late March).
Residents of the Coachella Valley with an unobstructed southern view on a very clear evening might enjoy searching for the star Canopus, the second-brightest nighttime star, after Sirius. From our latitude of 34 degrees north, Canopus passes 3-4 degrees above the south point of our horizon some 21-22 minutes before Sirius reaches its high point. On March 6, Canopus attains its high point just as evening twilight ends, 1.4 hours after sunset, and then gets nearly four minutes earlier daily. You might appreciate having a bit of twilight during your search, allowing you to use your distant horizon landscape as a reference, so the evenings of March 9-12 might be best. If you spot Canopus one evening and return to the same site on the following evening, the star will appear in the same place three minutes and 56 seconds earlier. On March 15, Canopus reaches its high point in mid-twilight. By that date, or a day or two later, as the star reaches its high point, the sky may be too bright to spot it easily.
Morning sky: Venus is too close to the sun to be seen, leaving recently emerged Jupiter (magnitude -2) as the brightest morning “star.” At mid-twilight in the course of March, Jupiter climbs from 5 degrees up to 16 degrees up in the east-southeast. Mercury (near magnitude 0) and Saturn(magnitude +0.7) appear close by, as described below. Zero-magnitude golden Arcturus, high in the southwest to west, and blue-white Vega, very high in the east-northeast, are the most prominent stars. Also look for these first-magnitude stars: Spica, 33 degrees to the lower left of Arcturus; Altair and Deneb, completing the Summer Triangle with Vega; and reddish Antares, heart of the Scorpion, in the south to south-southwest.
The moon at dawn: About an hour before sunrise through March 10, the moon makes an eventful trek across the morning sky, passing first-magnitude stars and three planets.
On March 2, the waning gibbous moon appears 5 degrees above Spica, while Mercury has moved to within 2 degrees to the upper right of Jupiter. On March 4, Mercury appears just 0.6 degrees above Jupiter. On March 5, the moon, just over half full and approaching last quarter, appears 5 degrees above Antares in the south, while Mercury appears at its least distance, 0.4 degrees to the left of Jupiter, and 9 degrees to the lower left of Saturn.
On March 9, find the 16 percent crescent moon in the southeast, with an impressive string of planets to its left and lower left. In order, starting closest to the moon, are Saturn, Jupiter (the brightest) and Mercury. On March 10, the 9 percent moon sits below the three-planet lineup, within 9 degrees to the lower left of Saturn, and 5 degrees to the lower right of Jupiter. Mercury is 4.5 degrees to the lower left of Jupiter that morning, while Saturn is just more than 9 degrees to Jupiter’s upper right. On March 11, the 4 percent crescent moon will have barely risen in the east-southeast in bright twilight, only half an hour before sunup.
On March 15, the three morning planets appear in a nearly straight line at 10-degree intervals. From the upper right to the lower left, they are Saturn, Jupiter and Mercury. Thereafter, Mercury rapidly recedes from Jupiter and sinks into brighter twilight.
The moon returns to the morning mid-twilight sky March 27 through April 9: It’ll be full on March 28, and will appear near Spica on March 29, and Antares on April 1.
After the epic close conjunction of Jupiter and Saturn at dusk on Dec. 21, 2020, the giant planets have reappeared at dawn while spreading apart, to 9 degrees on March 9; 10 degrees on March 16; 11 degrees on March 24; and 12 degrees on April 2. The gap between them in the predawn sky will continue to grow until June 11, when they’ll be 19 3/4 degrees apart. On five occasions during 2029-31, Jupiter and Saturn will be 180 degrees apart! Their next conjunction, 1.1 degrees apart, will take place on Oct. 31, 2040.
On Aug. 1 and 19, 2021, the Earth will overtake Saturn and Jupiter, and those showpiece giant planets will be up all night, remaining visible during evenings for nearly a half-year thereafter. In the last five months of 2021, Venus, Jupiter and Saturn will all be available for evening naked-eye and telescopic observation. Let’s hope that conditions will be right by then for folks to gather to share and enjoy the wonderful views.