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The Sky of September
Dr. Wayne Wooten
Professor of Astronomy
Escambia Amateur Astronomers' Association
For September, the Moon will be just past new on September 1st. The first two weeks of September will thus find the Moon waxing and setting later each evening. Venus is now back into the evening sky, and a slender waxing
crescent moon passes south of it and fainter Mercury in the twilight on September 1st. Fainter Mars lies just to the upper left of the two innermost planets on that evening; binoculars may help find the two fainter planets, if skies are clear enough. First quarter
moon is on September 7th. The gibbous moon passes 3 degrees south of brilliant Jupiter in the SE on September 9th, and the Harvest Moon, the Full Moon closest to the Autumnal Equinox, occurs on September 15th. The last two weeks find the moon waning in the morning
sky. Last quarter moon sits high in the sky and half-lit at sunrise on September 22th, the day of the Equinox at 10:44 AM CDT.
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 August 31st visit the www.skymaps.com website and download the map for September 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 September 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 SE just after sunset at month's beginning; covered with sulfuric acid clouds, her bright tiny, almost fully lit disk reveals no visible details in the scopes.
She is passed by faster Mercury on September 12th; Mercury in turn passes even slower Mars on the 22nd. But by month's end, both Mercury and Mars are becoming lost in the Sun’s glare, while Venus will be the queen of the
evening for the next six 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. It is this time of year at an American Indian legend tells of the Bear and three hunters. The bowl is the bear, the three handle stars of the dipper the hunters. The first carries a
bow, and has shot the bear in its flanks. The second optimistically carries a bowl on his shoulder for bear stew; look closely, and you can see the pot (Mizar. horse in Arabic, and Alcor its rider more traditionally). The last hunter carries firewood for the feast.
The wound is minor, and the bear has not lost a step, but in the fall, as the bear goes into hiding along the NW horizon, the wound opens slightly, and blood oozes out to fall on the tree leaves and paint them red this time of year.
From the Dipper’s handle, we ‘arc' SE to bright orange Arcturus, the brightest star of Spring. Spike south to Spica, the hot blue star in Virgo. Note that Spica is now low in the SW, and by
September’s end, will be lost in the Sun’s glare due to our annual revolution of the Sun making it appear to move one degree per day eastward. To the Greeks, Spica and Virgo were associate with Persephone, the daughter of Ceres, goddess of the harvest. In their
version of ‘Judge Judy', the beautiful young daughter falls for the gruff, dark god of the underworld, Pluto. He elopes with her, much to the disapproval of mother Ceres, and they marry in his underworld kingdom of
Hades…a honeymoon in hell…really, he does love her as well, and the marriage itself works well. But it is the reaction of Ceres that creates alarm. Very despondent over the loss of her young daughter to a fate as bad as death, Ceres abandons the crops, which wither.
Soon famine sets in, and humanity appeals to Jupiter to save us all. Calling all together, Jupiter hears that Ceres wants the marriage annulled, Persephone loves them both, and Pluto wants his mother in law to stop meddling. Solomon style, Jupiter decides to split
her up, not literally, but in terms of time. In the compromise (aren’t all marriages so?), when you can see Spica rising in the east in March, it means to plant your peas. For the next six months, she visits upstairs with as very happy mama, and the crops will
prosper. But now, as Spica heads west (to the kingdom of death, in most ancient legends) for six months of conjugal bliss with Pluto, it is time to get your corn in the crib. This simple story, told in some form for as long as Noah’s flood, was one of the ways our
ancestors 7,000 years ago knew the solar calendar and when to plant and harvest. As you watch Spica fade, thank this star for agriculture, and in a certain sense, even our own culture.
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. A little east is our telescopic treat for September, the fine globular
cluster M-22, just to the upper left in the same binocular field as the star at the top of Sagittarius’ teapot. This colorful beehive of aging stars was recorded by EAAA astrophotographer Bob Gaskin of Destin, taking advantage of clear Walton County skies (Oh, I
miss them!).
In adjacent zodiacal sign 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.
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 northeast of Vega is Deneb, the brightest star of Cygnus the Swan. Merry Edenton-Wooten’s fine wide angle 30 minute time exposure of Lyra and Cygnus shows well the vast ‘Great
Rift Nebula’, a vast cloud of interstellar dust lying directly in front of the solar system as we orbit the Galaxy every 250 million years. It is possible the passage of our system through this dust will in a few thousand years cool down the earth into another ice
age, but that is not the answer to our global warming problem for this century! To the south is Altair, the brightest star of Aquila the Eagle, the third member of the three bright stars that make the Summer Triangle so obvious in the NE these clear September
evenings.
We plan to host public stargazes at the Fort Pickens Gate on Friday, August 29, and again on Friday, September 26th, and October 24th. We will set up just at sunset. 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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