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SYFY WIRE Bad Astronomy

Waxing Crescent Ceres

By Phil Plait

Apropos of nothing, please enjoy this lovely mosaic of the asteroid Ceres, created from a series of images taken by the Dawn spacecraft from April 24–26, 2015:

Yowza. That’s a big beautiful icy rock.

On the April 23, Dawn entered its science orbit, settling down after its long approach to Ceres. It’s in a circular polar orbit at a height of 13,500 kilometers over the surface. It takes about two weeks to circle the asteroid once.

Do you have red/green glasses? Try this 3-D anaglyph of Ceres, too. It really makes that double impact crater in the middle pop.

I’m very curious to see high-resolution images of the bright spots in the big crater we’ve been seeing, especially over time. There are hints that the two spots are actually several blurred together, so it’ll be very interesting to see what they look like. A friend pointed out to me that they’re not as bright as you might think; it’s just that Ceres is really dark. It reflects, on average, about 9 percent of the light that falls on it. Dawn’s other target, the asteroid Vesta, has a reflectivity of more like 43 percent!

Anyway, we’ll learn more over time as scientists get a chance to analyze the new hi-res data. It’s nice to see a mission just getting started with a new target even as MESSENGER ends its life on Mercury. Hopefully, the White House and Congress will fund more planetary missions; right now there aren’t any big ones being planned or built. Wouldn’t it be nice to see some Cassini-class missions orbiting a half-dozen outer solar system bodies? 

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