Navy's "The Sky This Week"

Nice blog on the Navy Oceanography Portal website featuring observational astronomy highlights of the week. - HLG


http://www.usno.navy.mil/USNO/tours-events/sky-this-week/the-sky-this-week-2009-december-8-15


The Sky This Week, 2009 December 8 - 15
The year's best meteor shower (that nobody ever sees)





--------------------------------------------------------------------------------

The Moon wanes in the morning sky this week, diving southward along the ecliptic into the realm of the summer constellations, which are beginning to give us a peek just before dawn. New Moon occurs on the 16th at 7:02 am Eastern Standard Time. Luna starts the week off in the company of golden Saturn, whom she courts on the mornings of the 9th and 10th. On the 11th the Moon may be found just four degrees southwest of the bright star Spica as morning twilight begins to gather.

The year’s earliest sunsets continue for the first half of the week, gradually moving later by the week’s end. By the 13th Old Sol sets a minute later than on the previous nights, but sunrise is still occurring progressively later each day. Thus, the year’s longest night is still to come, falling on the solstice on the 21st.

Most of us tend to spend these long, chilly December nights preparing our homes for the upcoming holidays, but you should try to make an effort to spend some time outdoors on the clearest evenings surrounding the night of December 13 – 14. This is the peak of the annual Geminid meteor shower, which is probably the most consistent display of its kind year in and year out. This shower was made for casual skywatchers. Its radiant is just west of the bright star Castor in Gemini, which is 40 degrees above the northeastern horizon by 10:00 pm. The meteors themselves are half the speed of summer’s Perseids or November’s fickle Leonids, and they are consistently numerous, with hourly rates exceeding 100 for observers in dark locations. Even city-bound and suburban viewers can expect to see a bright meteor every minute or two, and this year the waning Moon is not a factor to further brighten urban skies. You should start looking for Geminids around 10:00 pm, but the best time to view will be around 1:00 to 2:00 am, when the radiant lies almost directly overhead. Ideally you’ll be in a location with an unobstructed view of the entire sky, lots of warm clothes, and a thermos full of hot cocoa. If it’s cloudy on the night of the 13th, the activity should be almost as strong on the preceding and following nights, and the shower continues with reasonable strength until the 16th. The Geminids have long been my favorite annual meteor shower, but for some reason it’s hard to convince friends and family to lie down on a lawn chair in an open field for a few hours at this time of year. At least there are no mosquitoes!

Jupiter still commands our attention as evening twilight fades. The giant planet is now settling in the southwest sky as darkness descends, but he still presents a pleasing view in the telescope. On the first few nights of the week use a low-power eyepiece to sweep east of Old Jove across a vertical line of three 5th magnitude stars. An imaginary line drawn from Jupiter through the center star will point you toward 7th magnitude Neptune. Jupiter moves across the line of stars early next week, then passes half a degree south of the solar system’s most distant major planet.

Ruddy Mars is now becoming quite prominent in the eastern sky as the midnight hour approaches. He is now the brightest object in the eastern sky except for Sirius, which provides a wonderful, ice-blue color contrast to Mars’ pink hue. His telescopic disc is steadily growing as Earth heads toward its rendezvous with the red planet in late January.

Saturn is high in the east as morning twilight begins to brighten the sky. He gets a visit from the Moon on the mornings of the 9th and 10th. Look for the stiletto extensions of his nearly edge-on rings, whose northern face is now brightening under the increasing illumination of the Sun