Daily Archives: February 15, 2010

Nits to Pick

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Blogs and news stories which list the most recent comment first. This makes no sense to me. There are comments on comments, and you need to read these chronologically to make any sense of them.

Blog archives not using previous and next (or the equivalent) in a consistent fashion. On some, previous takes you to the previously viewed page, which has a more recent timestamp, but on others it takes you to an earlier set of posts.

Sites which append their URL when you copy & paste anything. I understand the reason — to make it more likely to drive traffic back to the original site. But for a responsible blogger, who is going to link back anyway, this is just an annoyance and makes it less likely I’ll grab the story from you, if it’s something being reported elsewhere.

Great Jumping Sand Grains, Batman!

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Martian Dune Mystery Solved by Bouncing Sand Grains

The way sand grains knock each other around turns out to make all the difference, Kok says. Because Martian gravity and air density are so much lower than Earth’s, a small kick from the wind sends sand particles on Mars flying much higher, up to a meter off the ground.

“It’s like playing golf on the moon,” Kok says. Particles get caught in stronger winds as they rise, causing them to pick up speed and ultimately slam into the ground, where they kick up more particles and start the cycle over. “This splashing process is really efficient,” Kok says. “It can keep saltation, or sand blowing, going on Mars at relatively low wind speeds.” These jumping sand grains can create ripples over time even without high sustained winds, he says.