Strange space objects called centaurs have recently been discovered in the far reaches of the solar system. Orbiting our Sun in a region called the Kuiper Belt, located beyond Pluto, centaurs are small objects-up to 125 miles (200 km) across; they now bridge the mini-planetoid classification gap between asteroids and comets.
Centaurs are a little bit like asteroids and a little bit like comets; they are composed of rock, ice, gases and various organic compounds. Water ice has been confirmed on a number of centaurs.
In deep space, far from the Sun, centaurs behave as nomad asteroids. But when a centaur occasionally wonders closer to the Sun, its surface ices boil off and the object becomes more comet-like, even developing a gauzy tail. These strange objects, like the dwarf-planet (or just plain planet) Pluto and its moons, are part of a vast debris field left over from the formation of the solar system 4.54 billion years ago.
Orbits of centaurs are highly unstable. Occasionally, Neptune's gravity field will affect a centaur's orbit nudging it closer to the Sun. When the centaur's surface heats up due to increased solar energy, some of its ice sublimes to sport a blunt comet's tail.
Chiron is the largest centaur object discovered so far. It's named after the mythological centaur named Chiron. Chiron is best remembered as the amazing tutor of both ancient Greek superheros Achilles and Hercules.
Originally classified as a deep-space asteroid, Chiron was reclassified as the first centaur in 1977.
A similar object, called Pholus, was discovered in 1992. Ever since, astronomers have been finding more centaur objects beyond Pluto's orbit. Despite the distance between Earth and the remote space pastures where centaurs roam, astronomers have been able to detect some surface color variations.
Most centaurs appear to be red due to similar chemicals, perhaps organics. Chiron, however, appears darker than its lonely companions. No one knows for sure, but this may be due to the fact that its original surface material has been boiled off countless times in its drunken-like orbit around the Sun. Then again maybe Chiron is more rocky than its fellow centaurs.