Pluto on the viewscreen, Captain. [View all]

[Octafish]

New Horizons Sees Features on Pluto!



by Phil Plait
Slate, April 29, 2015

At a press conference on Wednesday astronomers working on the New Horizons space probe revealed new images that show surface features on Pluto for the first time!

The probe was just over 100 million kilometers from Pluto when the images were taken on April 12–18 (the Earth is 150 million km from the Sun, for comparison). Hubble images taken over the years have shown the diminutive world has darker and lighter patches on its surface, and these images match that.

In fact, these images are now at higher resolution than Hubble can produce! And they'll be getting better every day ...

Pluto looks lumpy in the animation, but that’s certainly an illusion; darker spots near the edge make it look like Pluto has chunks taken out of it. It’s expected that Pluto will be quite round; its gravity should compress it enough for it to be mostly spherical. I wonder if it’ll be oblate (slightly flattened) due to tides from its moon Charon. We’ll know pretty soon.

Charon can be seen in the animation as well, orbiting Pluto once every six days or so. Actually, it’s about ¼ the diameter of Pluto, and massive enough that it pulls on its parent pretty hard, hard enough that it’s more correct to say they both orbit their common barycenter, their center of mass.

Great links, more:

http://www.slate.com/blogs/bad_astronomy/2015/04/29/pluto_new_horizons_sees_surface_features_for_the_first_time.html

Imaging promises to get better and better till the July fly-by, and that should be something too, as scientists can use the sun shining through the Plutonic atmosphere to get an idea of its composition.