The Night Sky of March

Dr. Wayne Wooten
Professor of Astronomy

For March the moon is waxing crescent Just below Venus and the Pleaides cluster in the west on March 1st. The full moon is on March 9th, the Grass Moon in tradition. The waning crescent moon passes below a close conjunction of brighter Jupiter and reddish Mars in the dawn sky on March 18th, a great photo op for early risers. It passes south of Saturn the following morning. The Vernal Equinox occurs also on March 19th, with spring beginning at 10:50 PM CDT. The new moon is March 24th, and the waxing crescent again passes Venus on the evening of March 27th.

Mercury is not well placed for viewing this month, and only Venus is in the evening sky. It reaches greatest eastern elongation, 46 degrees from the Sun, on March 24th. On the edge of its orbit as seen by us, it appears half lit in the western sky with a telescope. In the weeks to come, it retrogrades westward, overtaking the slower moving earth. Is gets closer and larger by the day, and now appears as a shrinking crescent in the scope. It passes between us and the sun in May, moving into the dawn sky for the rest of 2020. In the March dawn, we have three bright planets changing positions by the day. Closer and faster Mars overtakes slower but brighter Jupiter on March 20th, then catches up to fainter Saturn on March 31st.

The constellation Cassiopeia makes a striking W in the NW. South of Cassiopeia is Andromeda’s hero, Perseus. Between him and Cassiopeia is the fine Double Cluster, faintly visible with the naked eye and two fine binocular objects in the same field. Perseus contains the famed eclipsing binary star Algol, where the Arabs imagined the eye of the gorgon Medusa would lie. It fades to a third its normal brightness for six out of every 70 hours, as a larger but cooler orange giant covers about 80% of the smaller but hotter and thus brighter companion as seen from Earth. At Perseus’ feet for the famed Pleiades cluster; they lie about 400 light-years distant, and over 250 stars are members of this fine group. East of the seven sisters is the V of stars marking the face of Taurus the Bull, with bright orange Aldebaran as his eye. The V of stars is the Hyades cluster, older than the blue Pleiades, but about half their distance. Yellow Capella, a giant star the same temperature and color as our much smaller Sun, dominates the overhead sky in the northwest. It is part of the pentagon on stars making up Auriga, the Charioteer (think Ben Hur). Several nice binocular Messier open clusters are found in the winter milky way here. East of Auriga, the twins, Castor and Pollux highlight the Gemini; it is directly above us as darkness falls in early March. UWF alumni can associate the pair with Jason and the Golden Fleece legend, for they were the first two Argonauts to sign up on his crew of adventurers.

South of Gemini, Orion is the most familiar winter constellation, dominating the southern sky at dusk. The reddish supergiant Betelguese marks his eastern shoulder, while blue-white supergiant Rigel stands opposite on his west knee. How bright does Betelguese appear to you tonight? In the past six month, this famed supergiant has expanded and cooled, forming a dust envelope that has darkened it to less than half normal brightness. Last I checked, it was down to the brightest of the three stars that make the belt, the faintest on record as seen by humans. Some speculate it might go supernova, becoming brighter than the full moon from a safe distance of about 700 light years; in fact, it might have done so 699 years ago, and we will find out about it next year?

Just south of the belt, hanging like a sword downward, is M-42, the Great Nebula of Orion, an outstanding binocular and telescopic stellar nursery. The bright diamond of four stars that light it up are the trapezium cluster, one of the finest sights in a telescope and among the youngest known stars.

In the east are the hunter’s two faithful companions, Canis major and minor. Procyon is the bright star in the little dog, and rises minutes before Sirius, the brightest star in the sky. Sirius dominates the SE sky as darkness falls. At 8 light years distance, Sirius is the closest star we can easily see with the naked eye.

When Sirius is highest, along our southern horizon look for the second brightest star, Canopus, getting just above the horizon and sparkling like an exquisite diamond as the turbulent winter air twists and turns this shaft of starlight, after a trip of about 200 years!

To the northeast, look for the bowl of the Big Dipper rising, with the top two stars, the pointers, giving you a line to find Polaris, the Pole Star. Here it sits unmoving 30 degrees high in on our northern sky locally. If you take the pointers of the Big Dipper’s bowl to the south, you are guided instead to the head of Leo the Lion rising in the east, looking much like the profile of the famed Sphinx.

The bright star at the Lion’s heart is Regulus, the "regal star". The folk wisdom that "March comes in like a Lion" probably refers to the head of Leo rising just after sunset in early March. It is the hind quarter of the Lion that we find our featured photo of March, the "Leo Trio" of galaxies, M-65 (normal spiral in upper right), M-66 (barred spiral below it), and NGC-3628 (gravitationally torn, edge on, at left).

If you follow the handle of the Big Dipper to the south, by 9 PM you will be able to "arc to Arcturus", the brightest star of Spring and distinctly orange in color. Its color is an indication of its uniqueness. Its large speed and direction through the Milky Way suggests it was not formed with our Galaxy, but is a recent capture from the Sagittarius Dwarf Galaxy, a smaller satellite galaxy now being assimilated by our huge spiral galaxy. Many of its lost stars, like Arcturus, follow a band across the sky at about a 70 degree angle to our galactic plane. Arcturus is at the tail of kite shaped Bootes, the celestial bear driver chasing the two bears from his flocks. Spike south then to Spica in Virgo. Here appearance to the Greeks marked the time to plant, for they associated Virgo with Persephone, daughter of Ceres of the Harvest, returning from six months underground with Pluto to now bless the growth and greening of the upperworld. So when Spica rises now at sunset in the SE, it is time to plant your peas! Likewise, when Persephone goes back down to Hades and disappears in the sun’s glare in September SW skies, it is time to get your corn in the crib! This cycle of planting and harvesting by this star goes back to the dawn of civilization.

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