Bad Astronomy

What, no monolith?

I can’t get enough animations of space.

Launched in September, 2007, the Japanese lunar probe SELENE (nicknamed Kaguya) has been snapping away, taking tremendous amounts of data of our only natural satellite. The images and animations have been spectacular, of course, and a new one is on their site that is totally cool: a 3D tour of the crater Tycho (warning: BIG file download).

Tycho is one of the youngest big craters on the Moon, with rays emanating from it caused by ejected rock and dust when whatever it was that smacked into the Moon splashed out ejecta for hundreds of kilometers. If Tycho were old, those rays would be erased by subsequent impacts.

When the Moon is full, Tycho is one of the most obvious lunar features. It’s one of the Moon’s iconic features (it’s also where Arthur C. Clarke put the monolith in 2001).

The animation from SELENE was created by combining imaging data with altitude measurements, allowing each piece of the crater to be mapped both as a picture and a height. Once you have that, you can tell the computer to map it from any angle, and voila! A tour is born. This is an amazing sequence; you really get a feel for the height of the central mountains (caused by the shock wave of the impact rebounding off the lunar material and refocusing into the center of the newly-formed crater, similar to how drops of milk or water splash back up when dripped into a full glass). The slumping of the material at the crater rim is also pretty incredible. The Lunar Picture of the Day has a high-res zoom of the central peak, and more info too. The image above is from SELENE (courtesy JAXA/SELENE).

When I look at the central peaks, I wonder how long it will be before some human stands there and looks around. It will happen, sometime. Maybe not in the next twenty years, or even fifty, but someday.