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The Sky of April

Dr. Wayne Wooten
Professor of Astronomy
Escambia Amateur Astronomers' Association

For April 2008, the Moon will be a waning crescent as the month begins. The waning crescent moon is passing about 4 degrees south of Venus on April 4th. The new moon occurs on April 6th. The next two weeks find the moon waxing in the evening sky. First quarter moon sits high in the sky and half-lit at sunset on April 12th, and will be just one degree north of red Mars. The gibbous moon sits 2.3 degrees south of Saturn on April 15th. The full moon occurs on April 20th; this is the Egg Moon in tradition, even if Easter was last month! The last quarter moon rises about midnight on April 27th, about three degrees south of bright Jupiter.

While the naked eye, dark adapted by several minutes away from any bright lights, is a wonderful instrument to stare up into deep space, far beyond our own Milky Way, binoculars are better for spotting specific deep sky objects. For a detailed map of northern hemisphere skies, about April 1st visit the www.skymaps.com website and download the map for the new month; it will have a more extensive calendar, and list of best objects for the naked eyes, binoculars, and scopes on the back of the map. Also available as the next month begins is wonderful video exploring the April 2008 sky, featuring many different objects, available from the Hubble Space Telescope website.

Venus is low in the east just before dawn. Jupiter dominates the morning sky, the brightest object well up in the southeast, rising about midnight. Red Mars is high overhead as darkness falls; it is much more distant and fainter than back near opposition last Christmas. It is now moving eastward from Gemini into Cancer in April. Saturn is in the east in Leo, just east of the brightest star in Leo, Regulus. This is the best time to observe the most beautiful object in the sky. When viewed with a telescope, this year the rings will be even more narrow than last year. In 2009, at Saturnís equinox, the edge on rings are so narrow they will disappear with most telescopes for several weeks.

Yellow Capella, a giant star the same temperature and color as our much smaller Sun, dominates the northwestern sky. 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. 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. 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.

To the northeast, look for the Big Dipper rising, with the top two stars of the bowl, the pointers, giving you a line to find Polaris, the Pole Star. Look for Mizar-Alcor, a nice naked eye double star, in the bend of the big dipperís handle. Take the pointers south instead to the head of Leo, looking much like the profile of the famed Sphinx. The bright star at the Lionís heart is Regulus, the 'regal star' but brighter still is Saturn, just east of Regulus.

Now take the curved handle of the Big Dipper, and follow the arc SE to bright orange Arcturus, the brightest star of the spring sky. Recent studies of its motion link it to the Sagittarius Dwarf Galaxy, a companion of our Milky Way being tidally disrupted and spilling its stars above and below the plane of the Milky Way, much like dust falling away from a decomposing comet nucleus. So this brightest star of Bootes the Bear Driver is apparently a refugee from another galaxy!

Now spike south to Spica, the blue-white gem in Virgo rising in the SE. Virgo is home to many galaxies, as we look away from the obscuring gas and dust in the plane of the Milky Way into deep space. One that like our own is quite dusty is M 104, the Sombrero, visible in binoculars west of Spica. Bob Gaskin shows the dust lanes well in his photo of this almost edge on spiral.

Continuing a tradition going back to the 1976 bicentennial, the EAAA will host a public stargaze at the gate for Fort Pickens on Friday evening, April 4th. We will set up at sunset, and use the dark skies to show you Saturn, Mars, and galaxies rising in the east, as well as the Orion Nebula and other winter treats. For more information on the Escambia Amateur Astronomers and our local star gazes for the public, visit our website at www.eaaa.net or call our sponsor, Dr. Wayne Wooten at PJC at (850) 484-1152, or e-mail him at wwooten@pjc.edu.

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