Dawn mission to Ceres

I've mentioned the dwarf planet Ceres in my posts before, but only in passing. it's a little hard to introduce Ceres, due to changing nomenclature. It used to be considered the largest asteroid, but it's now called a dwarf planet. It's certainly the largest object found in the asteroid belt between Mars and Jupiter. It's also the only defined dwarf planet this side of Neptune.

We've known about Ceres since the start of the 19th Century. Astronomers had been looking for planets between Mars and Jupiter, and discovered a number. They called this group "asteroids", meaning things that are "almost, but not quite, entirely unlike stars".

But the thing that's most interesting about Ceres is those white dots. Hubble got a few photos of odd bright patches on Ceres back in 2004. Aliens? Yeah, naah.

The Dawn mission, when a probe orbited Ceres, found that these were patches of sodium carbonate. These had probably formed when salty water bubbled up from Ceres' "muddy" interior, the water then sublimating into space.

Judging from the amount of mixing the surface gets from meteorites, the percolation of brine to the surface is still happening, meaning Ceres is still volcanically active.

You can see Ceres. It's a bit of a challenge, though. 

Ceres is magnitude 7.7, so you're going to need a medium sized telescope, a tracking mount and a camera. You'll need to figure out where it's going to be by using Stellarium, Cartes du Ciel or some similar planetarium program. Ideally, you'll be doing this at the time of year when Ceres rises at about sunset sets at about sunrise, which would mean it's well-placed for observation. If you've got a go-to mount, it can be very useful to find closest star with an SAO catalogue number - that way you can find that star with your mount.

To see Ceres, take an exposure of about 30 seconds while your mount is tracking. Then about an hour later, come back and take another one. Better still, keep taking images for a few hours. Ceres will be the dot that moves slowly across the face of the other stars. And I do mean slowly. My field is about 1.8° wide, and Ceres takes about 10 days to cross this.

Good luck!

...and apologies to Douglas Adams.

NASA images/Stellarium