Stargazing from Sky & Telescope Magazine
Touring the March Sky - A seasonal divide splits the sky between east and west — even before the official end of winter and start of spring.
by Alan MacRobert
Windy March nights display a starry sky that’s in rapid transition, with new constellations seeming to sweep away old ones almost as fast as the racing night-winds. It’s not just your imagination. Sunset and nightfall are coming later and later now, which means you’re probably going out to starwatch at a later hour — and that makes the seasonal changing of the constellations seem to speed up.
Goodbye to Winter
Just as March itself is split between winter and spring (which this year begins on the 20th), so the March evening sky is split between “winter constellations” heading off to the west and “spring constellations” taking over from the east.
Let’s start with the bright winter sights. Outshining all other stars is Sirius, sparkling whitely high in the south af-ter dusk. Sirius appears so bright for two reasons. First, it emits 23 times as much light as our Sun does, and second, it’s only 8.6 light-years away. In fact, Sirius is the closest star to Earth (not counting the Sun) that’s ever visible to the unaided eye from the latitudes of most of North America.
If you’re wondering about those qualifiers, here’s why I had to put them in. From south Florida you can spot the bright star Alpha Centauri, which at a distance of only 4.4 light-years is even closer than Sirius. And even from far-ther north, with a telescope you can pick out a couple of very faint red-dwarf stars that are invisible to the eye but, at distances of 5.9 and 8.3 light-years, are also closer than Sirius.
To the left of Sirius, in the southwest, the bright winter constellation Orion is descending for the season, with bril-liant Sirius off to its left. The eye-catching three-star belt of Orion, in the constellation’s middle, is now more or less horizontal.
To the right of Orion is Taurus, the Bull, highlighted by the orange star Aldebaran and, this season, the orange planet Mars. These two look remarkably similar right now, since Mars has faded greatly from its glory days of bril-liance when passing close to Earth last fall.
High above Sirius is Procyon, another near-neighbor star, at a distance of 11 light-years. And even higher, nearly overhead, are Saturn, Pollux, and Castor.
The Dipper and the Lion
Turn to the east after dark, the side of the sky where each new season’s stars first arrive, and what do you see?
Let’s start with the Big Dipper, which is already getting quite high in the northeast. Look for it standing there on its handle and starting to tip over to the left.
Follow the curve of the Big Dipper’s handle down and around to the right, for a bit more than one Dipper-length, and there you’ll be at bright Arcturus, which I’ve always thought of as the Spring Star. Arcturus’s ascent in the evening sky parallels the rising of the thermometer in March, April, and May.
The Dipper’s curving handle can also guide you to a lesser-known sight. If you picture the handle and the side of the Dipper bowl that’s attached to it as a segment of a circle (okay, a banged-up circle), then at the circle’s center is the modestly bright star Cor Caroli — a gorgeous double star for viewing in any telescope.
Mizar, the middle star of the Dipper’s handle, is also a double star — in three different ways. With reasonably sharp vision (or binoculars) you can see its faint little companion star Alcor tucked just to its lower left. A small telescope magnifying a mere 25´ splits Mizar and Alcor widely — and also shows that Mizar itself consists of two white suns closely paired. In addition, astronomers analyzing the light of Mizar’s two components have found that each of these in turn is a pair of stars orbiting each other too closely for any telescope to resolve.
Look way off to the Big Dipper’s right, due east, for the springtime constellation Leo, the Lion, sporting blue-white Regulus in its upper right side.
At a Glance
March 1 — Look for Mercury far below the crescent Moon in the west after sunset (see the first panel on the facing page).
March 4 — Mars and Aldebaran are far upper left of the Moon. All this week, Mars is about 7° upper right of Aldebaran.
March 10 — Saturn is the “star” near the Moon tonight.
March 14 — Full Moon, called the Egg Moon. A slight, penumbral eclipse, best seen from Europe and Africa, occurs as the Moon skims through the outermost fringe of Earth’s shadow. From the northeastern U.S. and the Canadian Maritimes, look for a very faint shading on the Moon’s right side as it rises in the east during twilight.
March 20 — The equinox occurs at 1:26 p.m. EST. This is when the Sun crosses the equator heading north for the year, marking the start of spring in the Northern Hemisphere.
March 25 — Venus is the bright “Morning Star” left or upper left of the crescent Moon, low in the east-southeast in early dawn. Venus is at its greatest elongation, 47° west of the Sun.
March 29 — A total eclipse of the Sun crosses parts of Africa, Turkey, and Central Asia.
First Quarter: March 6, 3:16 p.m. EST
Full Moon: March 14, 6:35 p.m.
Last Quarter: March 22, 2:11 p.m.
New Moon: March 29, 5:15 a.m.
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