2006-09-21 16:15:11 · 19 answers · asked by ~Lil mizz HollWood~ 1 in Science & Mathematics ➔ Astronomy & Space
Let's forget IAU definitions of planets for the moment and just ask: which is the coldest planetoid object in the Solar System?
Eris at aphelion (farthest away from the Sun) is 97 AU from the Sun as compared to Pluto which is a mere 49 AU at aphelion, ie twice as far out as Pluto and correspondingly colder.
However Sedna at aphelion gets to be a whopping 975 AU, 20 times as far away as Pluto ever gets.
As regards exoplanets (around other stars) the likely candidate for the coldest known terrestrial planet discovered thus far is OGLE-2005-BLG-390L b orbiting a red dwarf star 21,500 light years away at 2.6 AU from its star, about the oribtal distance of Ceres from the Sun. It has a mass of 5.5 Earth masses, making it the lightest exoplanet found so far.
Almost certainly there are smaller planets and planets further away from their suns than that but our technuques for finding them are still relatively rudimentary, with heavier objects near their stars being the easiest to find.
Watch this space.
2006-09-21 18:59:11 · answer #1 · answered by Anonymous · 3⤊ 0⤋
It used to be Pluto, but now it's not a planet anymore so, it's Neptune.
The coldest moon in the solar system that orbits a planet is Triton, A moon of Neptune.
2006-09-21 16:20:54 · answer #2 · answered by Eddy G 2 · 1⤊ 0⤋
Believe it or not, one of the coldest places in the Solar System is close to the Sun; the side of Mercury that never sees the Sun. It's at a similar temperature to Pluto or Neptune. Mercury has no atmosphere to carry heat to the cold side.
2006-09-21 16:24:30 · answer #3 · answered by zee_prime 6 · 1⤊ 0⤋
Neptune. It's farthest from the sun and temps on its dark side can approach absolute 0. The closest planet to the sun, Mercury, reaches 275 degrees below zero on its dark side. Pluto doesn't count any more since it's been demoted but it's as cold as Neptune.
2006-09-21 16:31:48 · answer #4 · answered by gone 7 · 0⤊ 1⤋
Since Pluto is not considered a planet in the Milky Way Galaxy anymore, I'd say in this galaxy it would be Neptune. Otherwise, oh the possibilities that are out there...
2006-09-21 16:24:09 · answer #5 · answered by Anonymous · 0⤊ 2⤋
is it true that pluto is soooo cold
2014-05-31 20:59:36 · answer #6 · answered by Daniel 1 · 1⤊ 0⤋
The planet formally known as xena, which is farther out than pluto, and far colder.
2006-09-21 16:40:14 · answer #7 · answered by khaoticwarchild 3 · 1⤊ 0⤋
The planet furtherest from the sun
2006-09-21 16:17:09 · answer #8 · answered by KAT 2 · 2⤊ 0⤋
Pluto If it's still around if not Neptune
2006-09-21 16:17:50 · answer #9 · answered by lilredbaby164 2 · 1⤊ 0⤋
planet furtherest from the sun-netune because pluto is no more a planet.
2006-09-22 00:17:27 · answer #10 · answered by Raven 6 · 0⤊ 1⤋