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The Night Sky of March

Dr. Wayne Wooten
Professor of Astronomy

For March 2015, the waxing gibbous moon passes 5 degrees south of Jupiter in the evening sky on March 3rd. The Moon will be full on March 5th; this is the Grass Moon. It wanes in the next two weeks of March, and reaches last quarter, half lit in the morning sky a week later, on March 8th. Our week is in fact based on observations of the quarter phases of the moon. Sunday, March 9th finds us springing forward to CDT. The waning gibbous moon passes 2.4 degrees north of Saturn on the morning of March 12th, and is at last quarter phase on March 13th, rising about midnight and half lit in the dawn sky. The waning crescent moon passes 5 degrees north of Mercury in the dawn on March 19th, and is new the following day. March 20th is also the Vernal Equinox; spring begins at 5:45 PM that day. This new moon also has a total solar eclipse, but only visible in the extreme Arctic regions, alas. March 21st finds the moon passing just south of reddish Mars in twilight, and then passing south of much brighter Venus the following evening. The Moon is first quarter phase on March 27th, and again passes close to Jupiter on March 30th, passing five degrees south of it. On April 4th, the full moon will the totally eclipsed, but this happens after sunrise for us locally; farther west, observers will get a much better view of this blood moon.

It is a great month to be observing the planets. Venus dominates the SW twilight after sunset, an almost fully bit disk now on the far side of the Sun. It shows no detail in its cloud tops for amateur telescopes. Likewise Mars lies on the far side of the Sun, and is a tiny red disk in the telescope. It will be lost on the Sunís glare by monthís end.

Jupiter is almost opposite Venus in the NE sky. Jupiter is bright and well up in the NE in Cancer at sunset as March begins. Small scopes reveal its four large Galilean Moons, and larger scopes show the belts and zones on the giant planetís disk, as well as the Great Red Spot, and even shadow transits as the moons pass in front of Jupiter and casting their shadows on the planetís rapidly rotating cloud tops.

Finally, Saturn is still in the morning sky in the claws of Scorpius, but will come to opposition in the evening sky on May 23rd, so those who stay up late can observe it rising in the east about 11 PM in mid March, and about 10 PM at the end of the month. The rings are tilting more open, so Saturn will be brighter this spring than last year.

The constellation Cassiopeia makes a striking W in the NW. South of Cassiopeia is Andromedaís 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 Perseusí 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. 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 hunterís 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 from West Florida.

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.

Look for Mizar-Alcor, a nice naked eye double star, in the bend of the big dipperís handle, rising by 7 PM at the start of March. Just south of the last star in the Dipperís handle is M-51, the famed Whirlpool Galaxy. Itís a great galaxy to look at as shows the difference in color between the hot young stars of the spiral galaxy and the aging yellow giants of the smaller elliptical galaxy that is passing just below it.

If you take the pointers of the Big Dipperís 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 Lionís 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.

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. It color is an indication of its uniqueness. It 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 celestrial bear driver chasing the two bears from his flocks.

By 9 PM, many more galaxies will be following as the Virgo Supercluster, ises in the east. This huge cluster of over a thousand galaxies is centered about 60 million light years away. The brightest star of Virgo, Spica, lies just east of the center of the cluster, and its rise just after sunset marks the time of year for spring planting in folklore. Time to get your peas in the groundÖ.March goes out like a lamb, not just from Easter tradition, but because Aries the Ram is setting in the west by the end of March. Many of our sayings and traditions have astronomical origins.

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