The only constant in space exploration is change. Researchers were reminded of this when the minor planet Chiron, orbiting the sun beyond Jupiter, revealed that it has rings. This makes Chiron the sixth object in the solar system known to have rings, made up of dust and gases, along with Saturn, Jupiter, Uranus, Neptune, and the minor planet Charilko.
Researchers discovered the rings when observing Chiron occulting a star in 2011. As Chiron’s shadow crossed the surface of the star, its shape revealed two sharp jutting features at the equator. These have been interpreted as rings, with two bands 3 and 7 kilometers wide, and a radius of 300 kilometers from Chiron’s center.
The occultation, observed through the NASA’s Infrared Telescope Facility, on Mauna Kea, and the Las Cumbres Observatory Global Telescope Network, at Haleakala, both in Hawaii, was viewed remotely by researchers at MIT.
Amanda Bosh of the Massachusetts Institute of Technology says that “There’s an aspect of serendipity to these observations. We need a certain amount of luck, waiting for Chiron to pass in front of a star that is bright enough. Chiron itself is small enough that the event is very short; if you blink, you might miss it.”
The minor planets are small rocky bodies orbiting the sun between Jupiter and Pluto. There may be as many as 44,000 of these in the solar system. Discovered only in 1977, they are called centaurs, after the mythical creatures that were a hybrid of horse and man. Centaurs are something between asteroid and comet, exhibiting aspects of each. While most centaurs are thought to be dormant, Chiron has been exhibiting signs of activity since the 1980s. In 1993 and 1994, Chiron was observed to have trails that looked like jets of water and dust.
Centaurs may be objects from further out in space that have had their orbits disturbed by the giant planets and pulled in closer to the sun. In that case, the rings may be matter that would have been frozen and stable further out, but turns into jets and rings closer to center of the solar system.
