Our Solar System’s Centaurs Are Half-Asteroid, Half-Comet

Understanding these ancient objects that sometimes produce cometlike tails may help explain how the solar system formed.
(Inside Science) — Centaurs are among the strangest objects in the solar system. The first, dubbed Chiron, was spotted orbiting more than a billion miles from the sun in 1977 and was originally thought to be an asteroid. But a few years later it was seen emitting a halo of gas — a “coma” — and a tail like a comet.
This dual nature gave these weird objects their name: Seemingly half-asteroid and half-comet, they were dubbed “centaurs” after the half-human, half-horse creatures of …