Chang’e-1 shoots the Moon

Contributed by
Nov 26, 2007

The Chinese Moon probe Chang'e-1 has returned its first picture of the Moon!

That's pretty cool! I wish I could tell you more, but the press release is in Chinese, and I'm a bit rusty.

It's funny with these Moon images being sent to us by Chang'e-1 and Kaguya; they don't look any different than what you can see through a telescope! But that's an illusion of sorts, caused by two things.

One is that these images aren't generally displayed at full resolution. They might really be thousands of pixels across, but they don't want to put a huge 100Mb file online. Hubble images are like that, which is why I down-res them and link to the higher-res versions.

The other reason is that the Moon is a weird place. It's been hopelessly battered from billions of years of bombardment from asteroids and comets. There are so many craters on its surface that it's saturated with them; literally, a new crater formed is likely to wipe out several craters at the same time. Also, without air, a crater can be formed from the impact of a basketball-sized rock as well as one the size of a city. So you get craters of all sizes on the Moon, and without any sort of scale to the pictures it's hard to tell how big they are. A picture taken from Apollo when the lander was 1000 meters up looks an awful lot like one taken from lunar orbit, even though the size scales are vastly different. There are some structural differences in craters of different sizes, but to the untrained eye they all look about the same.

Anyway, on the press release image there is a scale bar, but it's small and fuzzy. I think it's saying that the image itself covers about 200 x 300 km of the Moon. In that case, the pixel size is very roughly half a kilometer per pixel, which is about what you can do from Earth using fancy imaging techniques... and the actual data will have a higher resolution (160 meters per pixel when all is said and done).

I certainly hope they release more detailed images as time goes on. We're entering a new age of lunar exploration, and there's a whole lot more to learn about our nearest neighbor in the sky.

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