Friday, December 19, 2008

Sunset on the Sea of Rains

All of these pictures were taken by afocal projection with an Orion XT6 Dobsonian telescope and Nikon Coolpix 4500 digital camera. The first two shots were made through an Orion Sirius 25mm Plossl eyepiece and Orion Shorty 2x Barlow lens. The bottom shot was made through an Orion Sirius 32mm Plossl.

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Wednesday, December 17, 2008

Quote of the Day

Sunday, December 14, 2008

Sea of Crises

a.k.a. Mare Crisium. A basalt-filled impact basin 376 miles in diameter and more than 3.8 billion years old. It's got some killer mountains around it, and it's a good place to go exploring right after a full moon, when the rest of the moon is still washed out in direct sunlight.

Conditions were suboptimal tonight. It was windy so the atmosphere was just roiling through the eyepiece, which makes for less than crisp photos. But it's supposed to rain all week so I gave it a whirl anyway.

Southeast of Mare Crisium are four big craters in an arc: Langrenus, Vendelinus, Petavius, and Furnerius, in order from closest to Crisium to furthest away. There are also a couple of cool valleys, Valis Palitzsch and Vallis Snellius. There are no true water-carved valleys on the moon. Some lunar valleys formed by faulting, some were carved by flowing lava (strange but true), and some are collapsed lava tubes.

Valles Palitzsch and Snellius formed another way: they were gouged out by immense chunks of crust blasted away from the impacts that formed the maria. Vallis Palitzsch is 82 miles long and 25 miles wide at the fat end. For reference, Mount Everest is less than 6 miles tall and Mauna Kea is just over 6 miles tall if you measure from the ocean floor. Neither would amount to much compared to the block of crust that dug out Vallis Palitzsch when it landed.

Vallis Snellius is another secondary impact feature, created by a chunk of debris from the impact that formed Mare Nectaris. It is narrower but longer, 367 miles long in all. Imagine a piece of rock several miles wide rolling from LA to San Francisco (actually some puritans would probably like to see that happen).

I wonder about the mountains, craters, and so on that were in the way of those juggernauts. I would like to have been around to watch them get flattened.

Some fun, huh?

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Saturday, December 13, 2008

Happy holidays from Hubble

If you've never had one, an advent calendar has 25 little boxes to open, one for every day of December through Christmas. has a virtual advent calendar of Hubble's greatest hits. This is a ring galaxy, from Dec. 6.

Hat tip to Jarrod, and Merry Christmas to all!

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Friday, December 12, 2008

Howl, baby

Taken by me, from my driveway, about two hours ago.

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Thursday, December 11, 2008

Read this paper

Wednesday, December 03, 2008

Quote of the day: Ebert on Bubba Ho-Tep