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The Night Sky of August

Dr. Wayne Wooten
Professor of Astronomy

For August 2017, waxing gibbous moon passes 3 degrees north of Saturn in the SE twilight on August 3rd. The full moon, the Green Corn Moon, is only August 7th. The Perseid meteor shower peaks on the morning of August 13th, with the last quarter moon rising about midnight and interfering somewhat with the fainter meteors. Expect about a meteor a minute coming out of the NE after midnight. The waning crescent moon passes two degrees south of Venus in the dawn on August 19th.

This new moon is a very special one, for the Moon sits on the ecliptic, directly in front of the Sun for observers in North America. For those on the center line from Salem, Oregon through Charleston, South Carolina, they will witness about 2 minutes of totality! This is the first “coast to coast” total solar eclipse since 1879, and the first totality in the United States since 1979. For those planning to observe from West Florida, we will see first contact, the beginning of the partial eclipse, about 12:05 PM locally on Monday, August 21st. The EAAA members will set up outside the Pensacola State College Planetarium, clear skies permitting, for public viewing and photographing the partial eclipse. Maximum coverage will be 82% at 1:37 PM, and the partial eclipse will send with the moon leaving the sun’s eastern limb at 3:03 PM.

The waxing crescent moon passes three degrees north of Jupiter in evening sky on August 25th, and the moon is first quarter on August 29th. The next total solar eclipse for America will be in 2024, and takes place well west of us, in Texas up through the NE into Canada.

Mercury is low in the western evening sky as August begins. Venus dominates the dawn sky. Mars lies behind the Sun. Jupiter is visible in SW twilight, but will be getting lost in the sun’s glare by September. Saturn is easily seen in the SE in Sagittarius. Enjoy the rings, now 27 degrees open and tilted toward earth and sun; the most beautiful planet falls closer to the western horizon each evening, to be lost in the sun’s glare in October.
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. From Spica 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. It is faintly visible with the naked eye under dark sky conditions, and among the best binoc objects on the map back page when you download the SkyMap pdf file.

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. If you scan the Milky Way with binocs or a small spotting scope between Altair and Deneb, you will find many nice open star clusters and also a lot of dark nebulae, the dust clouds from which new stars will be born in the future

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! Just above the tail of the Scorpion are two fine naked eye star clusters, M-7 (discovered by Ptolemy and included in his catalog about 200 AD) and M-6, making one of the best binocular views in the sky. Your binoculars are ideally suited to reveal many fine open star clusters and nebulae in this region of our Galaxy. Get a dark sky site, and use the objects listed on the back of the August 2017 SkyMap printout to guide you to the best deep sky wonders for binocs.

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. In the same binocular field just north of the Lagoon is M-20, the Trifid Nebula. Our featured photo is by new EAAA member Orlando DeJesus, with his 8” telescope. The Trifid is indeed broken into three parts by the dust lanes he has shown so well. Just east of the pair is the fine globular cluster M-22, faintly visible to the naked eye and spectacularly resolved in scopes of 8” or larger aperture.

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