2010-08-01 / Nightlife

August brings annual celestial firework show

By Dr. Wayne Wooten
Pensacola Junior College

The “dumbbell” nebula, photographed by EAAA member John VeDepo. Submitted photo The “dumbbell” nebula, photographed by EAAA member John VeDepo. Submitted photo The month of August marks the arrival of the Perseid Meteor Shower, our best annual celestial fireworks show. The peak viewing night will be August 12, when the Moon will be a thin crescent and setting in early evening; so it will not be a factor 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. They will seem to come out of the constellation Perseus, rising in the NE just before midnight.

The first two weeks find the moon a crescent in the morning sky and evening skies, making the darker skies idea for observing the Milky Way. The first quarter moon is on August 16, and the Full Moon (Green Corn Moon in Native American lore) is on August 24.

Mercury will be visible in the evening sky in early August, reaching a greatest elongation of 27 degrees east of the sun on August 7, but it retrogrades in the next week and will be lost in sun's glare by midmonth. Venus dominates the western sky for the rest of the year, and moves below Saturn on August 8, then passes below Mars on August 19.

Mars too lies in the evening sky, but is very distant from earth and is not the bright object you may hear 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.

Those who are used to seeing Jupiter will be surprised by the lack of its southern "racing strike", the usually very prominent south equatorial belt, which vanished this spring and has not grown back to date.

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.

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.

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 fine stellar tombstone is our astrophoto highlight of the month. The "dumbbell" nebula was photographed by Escambia Amateur Astronomers Association (EAAA) member John VeDepo with his 18" scope and a MalinCam video camera, and is one of the most colorful and photogenic deep sky objects to observe with small scopes.

The EAAA plans to come back to Ft. Pickens on August 6 for new moon deep sky observing. They will set up around sunset at Battery Langdon Parking Lot.

They return to the Pavilion in Pensacola Beach for our sidewalk astronomy gazes on August 13-14 for our Perseid watch.

For more information on the Escambia Amateur Astronomers, visit the website or contact Dr. Wayne Wooten at (850) 484-1152 or wwooten@pjc.edu.

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