Archive for October, 2010

The Night Sky : This Week : October 12 – 19, 2010 !

The Sky This Week, 2010 October 12 – 19

An Ancient Story of the Season

jup12_101011_0145_02small.jpg
Jupiter, 2010 OCT 11, 01:45 UT
Imaged with the USNO’s 30.5-cm (12-inch) f/15 Clark/Saegmüller refractor

The Moon skims along the southern horizon this week, passing through the setting summer constellations before climbing back towards the north through the fainter stars of autumn. First Quarter occurs on the 14th at 5:27 pm Eastern Daylight Time. Luna lies just above the teapot-shaped asterism formed by the brighter stars of Sagittarius, the Archer, on the evening of the 13th. From there she treads a lonely path until the night of the 19th, when she passes about six degrees north of bright Jupiter.

The middle of October is one of my favorite times of the year. The seasonal change is almost as dramatic as the one that takes place in the spring, but instead of awakening from a long winter’s slumber the Earth is preparing for the coming lean times. Right now it feels as if my neighborhood is under some sort of siege as the oak trees drop their seemingly endless supply of acorns, while farther north the colors of changing leaves splash a riot of color over the landscape. These changes can be found steeped in the sky lore of cultures around the world. One of my favorite sky stories comes from the Native Americans of my New England home and involves one of the most recognized star patterns in the sky. Every year during autumn the seven stars that form the “Big Dipper” asterism graze the northern horizon during the late night and early morning hours of mid-October. The Big Dipper is part of the larger constellation of Ursa Major, the Greater Bear, in our Greco-Roman sky myths. To the natives who lived in the Berkshire Mountains of western Massachusetts and Connecticut, the Dipper also represented a bear, or at least the stars of the Dipper’s “bowl” did. The three stars of the handle represented three hunters, who chased the bear around the sky all year until this time of the year, when they finally caught it and killed it. The flaming red color of the changing maple trees in their world were thought to be stained by the blood shed from the bear’s wounds. If you look closely at the star that forms the “bend” in the Dipper’s handle, you might see a faint star nestled next to the brighter one. This was the pot that the hunters would use to cook the slain bear!

The early evening still offers keen-eyed skywatchers a fleeting glimpse of the planet Mars. He is currently traversing the faint stars of Libra on his way toward a conjunction with his ruddy rival, the star Antares, in November. You’ll probably need binoculars to pick the red planet out in the deepening twilight of the west-southwest sky, where he sets an hour and 20 minutes after sunset.

Much easier to spot is giant Jupiter, whose bright glow may be seen low in the east shortly after sunset. As the sky darkens he climbs higher into the southeastern sky, and by the end of evening twilight he is well placed for telescopic viewing. He now culminates high in the south at around 11:30 pm, which allows for several hours of fascinating viewing through the telescope. Jupiter’s four large “Galilean” moons offer an endlessly shifting configuration from night to night, while his famous Great Red Spot offers an interesting and colorful target for patient observers who observe him at the right times. Good nights to look for the Spot this week are the evenings of the 15th and 17th at around 10:00 pm EDT.

Advertisements

The Night Sky : This Week : October 5 – 12, 2010 !

The Sky This Week, 2010 October 5 – 12

Triangles, Squares, Jupiter, and a Comet!

jupc8_101003_0340_02small.jpg
Jupiter, with the Great Red Spot and “Little Red”
Imaged on 2010 OCT 3, 03:40 UT
from Alexandria, Virginia, USA

The Moon returns to the evening sky as a waxing crescent as the week ends. New Moon occurs on the 7th at 2:44 pm Eastern Daylight Time. Look for Luna’s fattening crescent in the southwestern sky shortly after sunset on the evening of the 9th. If you have a pair of binoculars, see if you can pick out the ruddy glow of the planet Mars about five degrees above the two-day crescent. Two nights later the Moon may be found about four degrees east of the ruddy star Antares, perched just above the southwest horizon as twilight ends.

You still have much of the week to enjoy the best of the autumnal sky before the Moon’s brightness begins to wash out the sky’s fainter objects. October has always been my favorite stargazing month, since the temperatures usually haven’t hit the freezing point yet and the summer’s best targets are still in view for the first couple of hours after dark. Evening astronomical twilight ends at around 8:15 pm, and at this time the stars of the Summer Triangle are directly overhead. The great star clouds of the Milky Way wend toward the southwest, and if you sweep the area between the Triangle and the horizon with binoculars or a small wide-field telescope you can catch many of the bright star clusters and nebulae that inhabit this stretch of the sky. By midnight another geometric figure, the “Great Square” of Pegasus straddles the meridian, with bright Jupiter parked just below. This area of the sky offers a “window” to distant external galaxies as we look south of the Milky Way’s plane. On clear nights from dark skies you can easily pick up the lozenge shape of misty light that betrays the Great Andromeda Galaxy in your binoculars, and if your surroundings are very dark you can easily see it with the naked eye. Draw an imaginary line from the lower right star in the Great Square through the upper left star to point yourself to our nearest large galactic neighbor. Larger telescopes reveal subtle detail in Andromeda’s delicate haze, and patient sweeping of the area around the square will show dozens of more distant galaxies to the sensitive eye.

High in the north at the midnight hour look for the “W”-shaped grouping of stars that portray Cassiopeia, one of the major figures in the Perseus-Andromeda myth. Binoculars and dark skies this week offer the possibility to see a fuzzy visitor to the inner solar system, Periodic Comet Hartley-2, which is making one of its closest approaches to Earth in its 6.46 year journey around the Sun. It will pass a mere 11 million miles from Earth on October 20th, and right now it is an easy target for binoculars and small telescopes. As the week opens it may be found below the left side of the “W” of Cassiopeia; as the week evolves it moves down toward the head of the wishbone-shaped constellation of Perseus. Look for a softly glowing greenish glow with a brighter center.

Jupiter is now the showpiece of the overnight hours. His bright glow has tricked many people into mistaking him for Venus, but the latter planet is now approaching solar conjunction and would never be found in this part of the sky at midnight. Old Jove has been rewarding owners of small to medium sized telescopes with wonderful views of his ever-changing cloud bands and shuttling moons. At a star party that I attended last weekend a young girl expressed delight at seeing the four Galilean moons in her rickety “department store” telescope. Her reaction at looking through several of the amateur telescopes set up nearby was even more enthusiastic. We’ll be able to continue enjoying Jupiter’s antics for the rest of the year, so keep an eye on him for constant changes.