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The Sky This Week, 2011 July 19 - 26

Remembering the end of another era...

Apollo 11 landing site, 1969 July 20
imaged 2009 May 31 from Alexandria, VA

The Moon climbs her way back toward the northern hemisphere constellations this week, drifting from the dim autumnal asterisms to the rising stars of the early winter sky. Last Quarter occurs on the 23rd at 1:02 am Eastern Daylight Time. Look for Luna near bright Jupiter on the mornings of the 23rd and 24th. On the morning of the 25th she may be found about four degrees west of the Pleiades star cluster. Just before dawn on the 27th, look for the Moon’s thinning crescent just over 3 degrees west of ruddy Mars.

It is hard to believe that July 20th marks the 42nd anniversary of humankind’s first tentative footsteps onto the surface of another world, but it was indeed on this day in 1969 that Neil Armstrong took that "giant leap for mankind". What is even harder to believe is that on the 21st we will retire the last active American passenger-carrying spacecraft as the shuttle Atlantis touches down in Florida for the final time. This happened once before as we recovered the final Apollo-era spacecraft at the end of the Apollo-Soyuz Test Project in 1975. It was nearly six years before the shuttle Columbia took its first flight. As someone who grew up in the heyday of the "Space Race", I followed every flight of the Mercury, Gemini, and Apollo programs which had taken us from a tentative, 15-minute sub-orbital hop in 1961 to Tranquility Base in just over eight years. I hope that it will not take us another six years to return to the exploration of these distant frontiers again.

The times of evening twilight’s end are now gradually shifting a little earlier each night, allowing us to enjoy some of the starry delights of the late spring and midsummer skies. High in the west we see the bright glimmer of the rose-tinted star Arcturus, brightest star in the northern hemisphere sky. In the northwest we can see the seven stars of the Big Dipper seemingly pointing to the bright star. In the east we find three bright blue-tinted stars, Vega, Altair, and Deneb, which make up the asterism known as the "Summer Triangle". By midnight the triangle is overhead, and skywatchers in dark-sky locations can see the heart of the summer Milky Way crossing the triangle and angling off to the southern horizon, where it passes between the red glimmer of the star Antares and the "Teapot" asterism of Sagittarius. When we look toward the part of the Milky Way that’s just above the teapot’s "spout", we’re looking toward the galactic center through an enormous cloud of innumerable distant stars. One of my favorite activities on summer vacation is simply gazing at these star clouds with a small-aperture low-power telescope.

Saturn still lingers in the southwest sky as twilight fades to darkness. You can still get a decent view of the ringed planet as soon as you can find it in the fading light. As the sky darkens the planet drops closer to the horizon, but if the air is still and not too hazy you can watch the planet’s various moons pop into view ad background light fades. The planet’s rings continue to slowly open to our view as well, promising a spectacular view for next year’s opposition.

Jupiter is steadily moving toward the evening sky, rising at around 12:30 am by the end of the week. The giant planet dominates the eastern sky as the wee hours slip by until dawn, and as morning twilight begins he’s well-placed for telescopic viewing. Old Jove’s South Equatorial Belt, usually one of his most prominent features, has returned to view after being AWOL for most of last year. Many amateur astronomers are taking advantage of the relatively cool morning air to get images of Jupiter. I may soon have to join them!

The ruddy glimmer of Mars may be seen just before dawn wending its way between the stars that form the "horns" of Taurus, the Bull. If you have trouble spotting the red planet, go out at around 5:00 am on the morning of the 27th. The waning crescent Moon will be just a few degrees west of Mars, offering you a convenient landmark to recognize him by as he drifts eastward toward the stars of Gemini.

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