Earth and Moon

This is a very simple image, but I don't think I've ever seen it before and I like it. It just shows Earth and the Moon and the distance between them to scale.



Found at the blog Page F30, in a post that argues that Ceres might be a better target for colonization than Mars.

UPDATE: A commenter points to a similar image at Wikipedia which also depicts the speed of light at the same scale.

Water on the Moon? Eh, Not So Much

Another astro-map from Universe Today. This one's of the moon:



It's a topographical map, recently put together with data from Japan's Kaguya satellite. It shows the crests and dales of the moon's surface, from the Dirichlet-Jackson Basin near the equator (11 km high) to the Antoniadi crater near the south pole (9 km deep). (Is it official policy, by the way, that place names on the moon be unpronounceable?)

But besides mapping the moon's topography, the Japanese researchers did a neat trick. They measured the roughness of the moon's surface, which allowed them to figure out if there's water underground. See, if there is water there, then it would act as a sort of lubricant, and the surface would exhibit more flexibility. But if there's no water, then the surface will be more rigid, just like the rough, rigid surface of a desiccated fruit. And the moon? Turns out it's pretty rigid. So: no water. Bummer.

What's that, David Byrne? You have something to say on the topic of water underground? A-and the moon, too?


Thank you, David. Thank you for that.