Mysteries of Pluto
Plutonian Puzzles
Spectral shift
Hubble Space Telescope observations show that Pluto became significantly redder from 2000 to 2002. This is thought to be due to seasonal changes in the ice surfaces as Pluto's distance from the Sun alters - but that two Earth-year interval is less than 1% of Pluto's year, so this is like major global seasonal changes on Earth taking place in just a few days.
|
Black moon
Of Pluto's five moons, four have similar colours and brightnesses, and all five seem to have formed together millions of years ago when an unknown object smashed into Pluto. Four are bright - yet Kerberos is black as coal.
|
Spotted worlds
Most of the surface of Pluto is covered by frozen nitrogen, with some frozen methane and carbon monoxide. But there is a bright white region at Pluto's north pole which seems to be entirely composed of solid carbon monoxide - no-one knowns why. And, Charon has an even more mysterious black spot.
|
Strange air
It used to be thought that as Pluto moves away from the Sun on its long orbit, its atmosphere must freeze and thin away to vacuum. But now it's no longer clear whether it thins, thickens or (as the attached link suggests) remains in place, kept thick through volcanic action.
|
Underworld ocean?
The close orbit of Pluto and its giant moon Charon cause enough internal heat generation inside Charon to form a meltwater ocean under the surface. Does Pluto have one too?
|
Moon crowd
The moons of planets can orbit at a wide range of distances (if they are closer than the "Roche Limit" they crash onto the planet, If they are further than the "Hill Radius" they drift away into space). The Moons of all the other outer planets are spread throughout these regions, but Pluto is different - all its moons huddle close.
|