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The Sky This Week, 2009 July 10 - 17

Saturn fades, Jupiter brightens, and the Moon joins Venus & Mars.

The Moon wanes in the morning sky this week, climbing through the faint stars of the autumnal constellations before ending up among the rising stars of winter.  Last Quarter occurs on the 15th at 5:43 am Eastern Daylight Time.  Look for Luna a few degrees east of bright Jupiter in the early morning hours of the 11th.  By the week’s end she’s closing in on Mars and Venus in the pre-dawn sky.  


As we move into the heart of summer many of us will be enjoying a break from the haze, heat, and humidity of the city.  Getting away to the mountains or the beach allows us to “recharge” a little as we prepare for the coming fall.  Even though the nights are short, the summer sky holds some of the sky’s most brilliant treasures, but you need to be well away from city lights to really enjoy them.  There’s something for everyone, whether they have just their unaided eyes, binoculars, or telescopes.  Some of my favorite stargazing sessions have occurred during our annual retreat to coastal New England, where I’ve sat for hours on a beach chair just watching the sky wheel slowly overhead.  From a dark beachfront the luminous haze of the Milky Way climbs from the eastern horizon to bisect the sky by the midnight hour.  The nature of the Galaxy’s light is very hard to describe in words; at best I call it a diaphanous haze interspersed with the glimmer of countless stars.  I especially enjoy looking at the dark “rifts” that are scattered through the hazy starlight.  These are clouds of dark material that screens the combined light of the star clouds behind them; they are the stuff from which we and the world we know as “home” are made.  For a little more detail, grab a pair of binoculars and sweep the portion of the Milky Way that pierces the heart of the Summer Triangle (the bright stars Vega, Deneb, and Altair).  The hazy glow breaks up into clouds of distant stars, and scattered through the clouds are brighter star clusters and clouds of glowing gas.  When I look up with my binoculars from my beach chair I often get the feeling that I am actually floating in deep space, lost among those distant Suns.


Much closer to home, Saturn still entertains, albeit briefly, in the early evening sky.  The ringed planet now sets just an hour after the end of evening astronomical twilight, so any telescopic viewing must be done while the sky is not fully dark.  This will limit your ability to detect the fainter moons, but you should still get a view of the rings.  With sunlight now striking them at an angle of only half a degree, they are much darker than they were a few weeks ago.


Bright Jupiter now rises about an hour before Saturn sets, and by the week’s end Old Jove peeks over the horizon at around 10:00 pm.  He will reach opposition in another month, so if you’re getting tired of coaxing detail from Saturn’s rather bland disc Jupiter will be there to get you excited again.  As more and more amateurs turn their telescopes toward the giant planet, they are being greeted with an outbreak of activity in the planet’s turbulent North Equatorial Cloud Belt.  These “NEB Outbreaks” can last for months at a time, and can dramatically change Jupiter’s appearance from night to night.


The pre-dawn sky still features the dazzle of bright Venus and the more subdued ruddy tone of Mars.  Both planets are drifting through the stars of Taurus, with Mars passing to the south of the Pleiades star cluster while Venus drifts eastward to the north of the Hyades.  By the week’s end the waning crescent Moon closes in on the pair.  On the morning of the 18th there will be a nice photo opportunity as twilight gathers.  The Moon, Venus, Mars, and the star clusters will pose together nicely in the faint light of dawn.