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The Sky of August

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

For August, the new Moon will be on August 1st; in Siberia and China a total solar eclipse will be seen. The first two weeks of August will thus find the Moon waxing and visible each evening. On August 2nd, you may spot the slender crescent Moon near Venus low in western twilight. First quarter moon is on August 8th, and the waxing gibbous moon passes below Jupiter on August 12-13th. The morning of August 12th is the peak for the Perseid Meteor Shower, our best annual celestial fireworks show. The Moon will set about 2 AM, so if you have a dark sky site, you will see about a meteor a minute from moonset until dawn. The Full moon occurs on August 16th. This full moon is the Green Corn Moon for native Americans. The last two weeks find the moon waning in the evening sky, making the darker skies idea for observing the Milky Way.

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 July 31st visit the www.skymaps.com website and download the map for August 2008; 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 August 2008 sky, featuring many different objects, available from the Hubble Space Telescope website at: http://hubblesite.org/explore_astronomy/tonights_sky/.

Venus is briefly visible low in the SW just after sunset at month’s beginning; she sets within about 40 minutes of sunset then. She appears as a tiny disk, about 97%lit on August 1stth. Only 10' across, you will need a telescope at about 50X to spot her phase, but she will already be the brightest thing in the western twilight, and dominate the western sky for the rest of this year. She is pulling away from the Sun, higher in the sky eacg evening. Covered with sulfuric acid clouds, her bright disk reveals no visible details in the scopes.

The Big Dipper rides high in the NW at sunset, but falls lower each evening. 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.

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. 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.

Hercules is overhead, with the nice globular cluster M-13 marked on your sky map and visible in binocs. Several other good globular clusters are also shown and listed on the best binoc objects on the map back page.

The brightest star of the northern hemisphere, Vega dominates the NE sky. Binoculars reveal the small star just to the NE of Vega, epsilon Lyrae, as a nice double. Larger telescopes at 150X reveal each of this pair is another close double, hence its nickname, the ‘double double’…a fine sight under steady sky conditions. Below Vega are the two bright stars of the Summer Triangle; Deneb is at the top of the Northern Cross, known as Cygnus the Swan to the Romans. It is one of the most luminous stars in our Galaxy, about 50,000 times brighter than our Sun. To the south is Altair, the brightest star of Aquila the Eagle. About midway between sits the planetary nebula M-27, visible in binoculars. This brightest of these stellar puffballs is nicknamed ‘the Dumbbell’, but it really is quite pretty; this fine photo by EAAA member John VeDepo show the central white dwarf star well in his 18' telescope.

To the south, Antares rises about the same time in Scorpius. It appears reddish (its Greek name means rival of Ares or Mars to the Latins) because it is half as hot as our yellow Sun; it is bright because it is a bloated red supergiant, big enough to swallow up our solar system all the way out to Saturn’s orbit!

East of the Scorpion’s tail is the teapot shape of Sagittarius, which marks the heart of our Milky Way galaxy. Looking like a cloud of steam coming out of the teapot’s spout is the fine Lagoon Nebula, M-8, easily visible with the naked eye. This stellar nursery is ablaze with new stars and steamers of gas and dust blown about in their energetic births. In the same binocular field just north of the Lagoon is M-20, the Trifid Nebula.

Just a little NE of Sagittarius, and much brighter, giant Jupiter dominates the SE sky. Any small scope will reveal what Galileo marveled at in 1609; four large moons, all bigger or similar to ours in size, orbit it in a line along Jupiter’s equator. So get out the old scope, and focus on Jupiter for a constantly changing dance of the moons around the giant world.

We plan to come back out the Ft. Pickens on August 1st for our deep sky session. We will set up just inside the gate. Bring out your lawn chairs and beach blankets. We return to the Pavilion in Pensacola Beach for our Perseid Watch on the weekend of August 8-9, 2008, to observe this fine natural fireworks display, with perhaps a meteor a minute coming out of the NE from the autumn constellation Perseus. Due to the geometry of our rotation and revolution, the peak will fall during the morning hours during this second weekend of August. In the evening, of course, we will have scopes set up, clear skies permitting, to allow you to observe Jupiter, nebulae, clusters, double stars, and other celestial treats. Free star charts and information on the EAAA will also be provided.

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