Mercury joins Jupiter at dusk; Venus, Mars up with dawn
Look up. There’s a lot to see. Here’s what it is in March.
Editor’s note: Times in this Night Words are standard time through March 9 and daylightsaving time starting with March 10.
Sunrise and sunset
• Sun rises at 6:34 a.m. and sets at 5:54 p.m. on the 1st
• Sun rises at 6:46 a.m. and sets at 7:25 p.m. on the 31st
Moon’s phases
• New moon on the 10th
• Full Worm Moon on the 25th
Stars and constellations
The month of March heralds the transition between the seasons of winter and spring: “in like a lion, out like a lamb.”
This change becomes apparent in the star patterns in the night sky as well, for the brilliant winter constellations will over the next several weeks be fading into the evening twilight, to be replaced by the generally less spectacular groups of spring.
As March opens, Aldebaran in Taurus and the compact star cluster Pleiades are still on display high in the southwest. Just west of overhead is Capella in Auriga, and Betelgeuse and Rigel in Orion are high in the south-southwest.
The “twin” stars Pollux and Castor in the constellation Gemini are high in the south, while just below the pair is Procyon in Canis Minor. And the brightest appearing star in the night sky, Sirius in Canis Major, shines with bluish-white radiance to Orion’s lower left.
The four brightest stars in Canis Major form a trapezoidal shape, consisting of Sirius (Alpha), Mirzam (Beta), Adhara (Epsilon), and Wezea (Delta), going clockwise from Sirius.
Sirius is by far the brightest of the foursome, with the other three stars having apparent brightnesses roughly comparable with the second-magnitude stars in the Big Dipper.
But the impression of relative brightnesses was found to be completely misleading, once astronomers determined distances to these objects.
Sirius, the “Dog Star,” is one of the sun’s nearest neighbors, at only 8.6 light-years distance. This distance was first deduced by trigonometric parallax in 1838 by the famous German astronomer and mathematician Friedrich Bessel. The other three are much farther away: Adhara is 480 light-years, Mirzam is 720 light-years, and Wezen is a whopping 3800 lightyears distant from our solar system.
As evening progresses into night, the stars of spring have begun to emerge from the eastern horizon.
Regulus, the brightest star in
Leo, stands high in the east by 9 p.m., and is one of the first spring stars to become visible after dark. The name Regulus denotes “royal,” and, indeed, Regulus was one of the four Royal Stars (along with Aldebaran, Fomalhaut and Antares) of the ancient Persian monarchy who were “guardians of the heavens.”
Regulus marks the lower part of what is Leo’s most distinctive feature: its “sickle,” which represents the mane of the lion.
In mythology, Leo represented the Nemean Lion which was slain as one of Hercules’ 12 labors.
Leo is, of course, one of the 12 zodiac constellations, with the sun passing within its borders between Aug. 10 and Sept. 16. Regulus is so close to the ecliptic path that it is occasionally occulted (eclipsed) by the moon.
Later at night, the Big Dipper, which is an asterism within the large constellation Ursa Major, gets higher in the northeast. The two front stars in the bowl of the Big Dipper, Merak and Dubhe, point toward the North Star, Polaris, while its handle “arcs” to yellow-orange Arcturus in the constellation Boötes, the Herdsman, which is rising in the northeast.
Arcturus is in fact the brightest star in the spring sky, and the fourth brightest star in the entire night sky.
Naked-eye planets
Mercury reached superior conjunction with the sun on Feb. 28, but this March it vaults above the western horizon at dusk, and gives its best evening showing of the year.
Mercury reaches maximum brightness around the 15th and then maximum elongation on the 24th, when it sets around 8:50 p.m. or about 1½ hours after the sun sets. Mercury is best viewed in the latter half of the month, about 20 to 30 minutes after sunset. Binoculars will help spot it.
Jupiter resembles a brilliant golden star ensconced among the much fainter stars of the constellation Aries.
The giant planet stands high in the southwest at dusk during March. It sets around 10:45 p.m. on the 1st, and by 10:15 p.m. on the 31st.
Jupiter’s presence in the evening sky will soon be coming to an end. It will sink into the evening twilight toward the end of April and reach conjunction with the sun in early May.
Venus has been a dazzling beacon in the early morning sky since autumn, but it will soon vanish into the morning twilight. As March opens, Venus is already very low in the southeastern sky, rising about one hour before sunrise.
Mars rises in the southeast about an hour before sunrise all month, which is by 5:20 a.m. on the 1st and by 5:30 a.m. at month’s end. Mars resembles a modest orange star hovering above the horizon, and it will not become bright and prominent until later this summer.
Mars will be at its best — 15 times brighter than it is now — when it reaches opposition with the sun in January.
Saturn was in conjunction with the sun on Feb. 28, and is too close to the sun to be visible as March begins, but it will reappear at dawn low in the east toward month’s end.
The noon sun stands directly over the equator at 11:06 p.m. on March 19. This point is the vernal equinox, which marks the start of spring in the northern hemisphere and of autumn in the southern hemisphere.
Test your smarts
• Astronomy question of the month: How old is the universe? (Answer will be provided in next month’s column.)
• Answer to last month’s question: The majority of stars are classified into one of seven main spectral classes: O, B, A, F, G, K, M, in decreasing order from hottest to coolest. They are further put into a finer spectral subclass, which ranges from 0 to 9 within each main class. Finally they are classified into one of six luminosity classes: I, II, III, IV, V, and VI, in decreasing order from brightest to faintest. In this scheme, the sun is classified as a G2 V, where the G2 is its spectral class/subclass, which indicates a surface temperature of about 5800 degrees Kelvin, and the V (Roman numeral five) tells us that the sun is a dwarf (also called a main-sequence star).
The fine print
• Astronomical information is obtained from The Astronomical Almanac (2021-2025) by Richard J. Bartlett, and from Astronomical Calendar 2024 by Guy Ottewell, available online at www.universalworkshop.com/astronomical-calendar-2024.
• For more information on the night sky, visit the Widener Observatory Stargazing website at www. widener.edu/stargazing.
• A set of free sky maps can be obtained at www.skymaps.com.