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The Night Sky of May

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

For May 2009, the Moon will be first quarter on May 1st. This is the ideal phase for getting out your small scope or binoculars and noting the rugged lunar surface first imaged by Galileo 400 years ago. My own shot of the Moon is of the 8 day old moon, with the large crater Copernicus just appearing in sunlight. How startled Galileo was to see such imperfections on our 'perfect heavenly companion'. The craters and mare showed the Moon was a world like our own in some ways, and this discovery lead him to more research with his primitive telescope, finally making him the champion of the Copernican system. On May 4th, the waxing gibbous moon passes about 2.5 degrees south of almost ringless Saturn, and the full moon occurs on May 9th. It is the flower or Strawberry moon in tradition. On the 17th, the last quarter moon rises about midnight, and is about three degrees north of Jupiter in the morning sky. The waning crescent moon passes by brilliant Venus on the morning of May 21st, passing six degrees north, and showing about the same crescent phase with the naked eye that Venus does in the telescope. The new moon occurs on May 24, and it will wax in the evening sky in the last week of this month. As the month began, so it also ends the first quarter moon occurs on May 31st, with it six degrees south of Saturn overhead.

While the naked eye, dark adapted by several minutes away from any bright lights, is a wonderful instrument to stare up at the Galaxy arching overhead, binoculars are better for spotting specific deep sky objects all along the plane of the Galaxy. For a detailed map of northern hemisphere skies, about April 30th visit website and download the map for May 2009; 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 May sky, available from the Hubble Space Telescope website at:

Saturn is the brightest object overhead as darkness falls. Its rings are almost edge-on at equinox now. You may also see some belts and zones on the planet's disk. The largest moon, Titan, will be seen in any small telescope, but smaller moons will need larger scopes to spot. As the planet is now only half are bright as when the bright rings are tilted more open, up to six moons may be spotted, in a straight line with the rings, with an eight inch telescope currently. To the west, Mercury puts on a nice display in the first week of May. It passes the Pleiades cluster on May 2nd, is at its highest in the evening sky at greatest eastern elongation on May 7th, then rapidly retrogrades between us and the Sun in the next week; it was not named for the speedy messenger god for nothing!

The winter constellations will soon be swallowed up in the Sun's glare, but Orion is still visible, with its famed Orion Nebula, M-42, seen below the three stars marking his famed belt. Dominating the southwest is the Dog Star, Sirius, brightest star of the night sky. When Sirius vanishes into the Sun's glare in two months, this sets the period as 'Dog Days'.

The brightest star in the NW is Capella, distinctively yellow in color. It is a giant star, almost exactly the same temperature as our Sun, but about 100X more luminous. Just south of it are the stellar twins, the Gemini, with Castor closer to Capella, and Pollux closer to the Little Dog Star, Procyon.

Overhead, the Big Dipper rides high. Good scouts know to take its leading pointers north to Polaris, the famed Pole Star. For us, it sits 30 degrees (our latitude) high in the north, while the rotating earth beneath makes all the other celestial bodies spin around it from east to west. If you drop south from the bowl of the Big Dipper, Leo the Lion rides high. Saturn lies just east of the bright star Regulus, the heart of the King of Beasts. Note the Egyptian Sphinx is based on the shape of this Lion in the sky.

Taking the arc in the Dipper's handle, we 'arc' SE to bright orange Arcturus, the brightest star of spring. Cooler than our yellow Sun, and much poorer in heavy elements, some believe its strange motion reveals it to be an invading star from another smaller galaxy, now colliding with the Milky Way in Sagittarius in the summer sky. Moving almost perpendicular to the plane of our Milky Way, Arcturus was the first star in the sky where its proper motion across the historic sky was noted, by Edmund Halley. Just east of Arcturus is Corona Borealis, the 'northern crown', a shapley Coronet that Miss America would gladly don, and one of few constellations that look like their name. The bright star in the crown's center is Gemma, the Gem Star.

Spike south to Spica, the hot blue star in Virgo, then curve to Corvus the Crow, a four sided grouping. It is above Corvus, in the arms of Virgo, where our large scopes will show members of the Virgo Supercluster, a swarm of over a thousand galaxies about 50 million light years away from us.

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