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The Night Sky of August

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

For August, the Full Moon will be on August 6th; in American Indian lore, this is the Green Corn moon. The first week of August will thus find the Moon waxing and visible each evening. This full moon finds the moon 3 degrees north of bright Jupiter in the SE.

The morning of August 12th is the peak for the Perseid Meteor Shower, our best annual celestial fireworks show. The Moon will be at third quarter on the 13th, rising about midnight, so it will overpower the fainter meteors when the radiant rises in the NE after midnight. If you have a dark sky site, you will see about a meteor every 2-3 minutes from midnight until dawn. T

he waning crescent moon passes 3 degrees north of Mars on August 16, and 1.7 degrees north of much brighter Venus the following morning. The new moon occurs on August 20th. The middle weeks find the moon waning in the morning sky, making the darker skies idea for observing the Milky Way.

The waxing crescent moon passes close to Saturn and Mercury in evening twilight on August 22nd, with all three objects in a straight line along the SW horizon about 8:15 PM CDT, with Mercury in the middle…a great photo op for digital camera users with a tripod mount shooting in night shot mode. The first quarter moon is on August 27th.

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.

Mercury will be visible in the evening sky in mid August. It passes 3 degrees south of Saturn in the twilight on August 17th, and both are in the line with the slendar waxing crescent moon on August 22nd. But both will be lost in the Sun's glare by month's end. Venus dominates the dawn for the rest of the year, the bright morning star. Mars too lies in the morning sky, very distant from earth and not the bright object you may head described in the recycled e-mails revived every August since its close approach to earth in 2003. These are urban legends that will not die, alas.

But August belongs to Jupiter, rising at sunset at opposition on August 14th. It will be the brightest object in the evening sky this August. Jupiter is now sporting not one but two big red spots, the second one in the northern hemisphere developing last spring, and its four large Galilean moons, spotted with a telescope 400 years ago this October, are constantly moving in front of it and casting their shadows on the giant of the planets.

Alas, Saturn is now rapidly disappearing behind the Sun in the western sky, so our August gazes will be the last glimpse at the almost closed rings for several months.

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.

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 in Capricornus. 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.

For a detailed map of northern hemisphere skies, visit the website and download the map for August 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.

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