[LINK] "Hubble catches Pluto red-faced"

[rfmcdonald]

Pluto as seen by the Hubble
Originally uploaded by rfmcdpei

Bad Astronomy has such great content.

these maps are more than just eye candy. They show significant changes on Pluto’s surface since the last maps were made using Hubble 16 years ago. Pluto’s north pole is brighter and the south pole darker, implying that material has migrated from one pole to the other, or at least that the poles are changing in different ways. Pluto orbits the Sun "on its side", dramatically more tilted than Earth’s mere 23.5°. Right now, the north pole of the world is facing the Sun, meaning it’s summer on Pluto’s northern hemisphere (as it’ll remain for a long time, given Pluto’s 248 Earth-year long year).

Not only that, these images show that Pluto has reddened quite a bit in the past few years. This is one reason it took so long to release the images; Marc Buie, the astronomer who took them, saw some things in the data that were difficult to understand, and wanted to make sure they were correct. These images are composites of pictures taken using a blue and a green filter. During the time these observations were made, in 2000 – 2002, Pluto got much darker in blue, which was unexpected. Pluto’s moon, Charon, did not get any bluer, indicating that the cause was something intrinsic to Pluto and not that something weird happened with Hubble.

So why is Pluto redder now? That’s not clear. In general, ultraviolet light from the Sun interacts with the chemicals on Pluto, creating reddish organic molecules; this is seen on lots of distant, icy objects in the Kuiper Belt (the region past Neptune where Pluto orbits). Incredibly, even at the numbing distance of over 4 billion kilometers (3 billion miles) from the Sun, Pluto is still strongly affected by it. But this is happening while overall the northern hemisphere got brighter and the southern darker. You’d expect Pluto to get darker if it gets redder, so clearly there’s more going on here than meets the eye.

I'd like live streaming high-resolution video from an array of science satellites in Pluto/Charon orbit, but this will do me for a while.