2060 Chiron

2060 Chiron is a special object in space that orbits the Sun between the planets Saturn and Uranus. It was discovered in 1977 by Charles Kowal and was the first of its kind to be found. These objects are called centaurs because they travel between the asteroid belt and the Kuiper belt. Chiron is named after a wise character from Greek mythology also called Chiron.

At first, Chiron was thought to be just an asteroid, a rocky object in space. But in 1989, scientists noticed that it behaved like a comet, which are icy bodies that can develop a tail when they get close to the Sun. Because of this, Chiron is now known both as a minor planet and as a comet, with the comet name 95P/Chiron.

More recently, between the 2010s and early 2020s, scientists observed Chiron during events called occultations. These events helped discover that Chiron has rings around it, just like some planets do. Chiron is one of only four minor planets known to have rings, along with 10199 Chariklo, Haumea, and Quaoar. It is also the only known comet with rings.

History

Discovery

Chiron was discovered on November 1, 1977, by Charles Kowal using images taken on October 18 at Palomar Observatory. At the time, it was the farthest known small planet from the Sun and was even called the tenth planet by some news reports. Later, scientists found images of Chiron going back to 1895, which helped them figure out its path around the Sun more accurately.

Naming

This small planet was named after Chiron, a wise half-human, half-horse character from Greek mythology. Chiron was known for teaching many famous Greek heroes. The official naming was announced on April 1, 1978. Most planets and small planets don’t have special symbols, but some people, especially astrologers, use a symbol that looks like a key for Chiron.

Orbit

Chiron moves in a very stretched path around the Sun, getting closest to the Sun near the orbit of Saturn and farthest out near Uranus. Its path does not actually reach Uranus’s usual distance.

Chiron was exciting because it was the first object found in such a special path, far beyond the asteroid belt. It belongs to a group called centaurs, which travel between the outer planets. These paths are not stable and will change due to the strong pull of the giant planets over millions of years. Chiron probably started in the Kuiper belt and may become a comet in about a million years. It was closest to the Sun in 1996 and farthest in May 2021.

Physical characteristics

The visible and near-infrared light from Chiron looks neutral, similar to some asteroids and comets. It shows gases like carbon dioxide, carbon monoxide, ethane, propane, and acetylene, along with water ice.

Observations of Chiron’s brightness over time show it rotates once every about 5.9 hours. Estimates of its size range from about 150 km to 218 km in diameter, but it’s tricky to pin down because Chiron sometimes acts like a comet. In 1988, Chiron brightened and developed a fuzzy atmosphere, or coma, which is typical comet behavior. Unlike most comets, water isn’t a big part of Chiron’s coma because it’s too far from the Sun to let water escape easily. Instead, small amounts of carbon monoxide and other gases were detected. Chiron is special because it’s both a comet (95P/Chiron) and a minor planet, showing how some objects fit into more than one group.

Rings

Chiron has rings, just like the rings around 10199 Chariklo. These rings were discovered after scientists noticed unusual changes in starlight when Chiron passed in front of stars. The rings are about 324 kilometers wide and change how they look from different angles, which helps explain why Chiron sometimes looks brighter or dimmer.

More recent observations in 2018 and 2022 showed that the rings around Chiron keep changing. In 2018, there was less material, but a new partial ring was forming. By 2022, the rings had more material, and the new ring was fully formed. Scientists think these changes happen in cycles. The rings of Chiron and Chariklo share many similarities, and both are within a certain distance from their centers that helps keep the rings in place.

Exploration

Scientists wanted to send a spacecraft to visit Chiron. They suggested a mission called the Chiron Orbiter Mission for NASA's New Frontiers program or Flagship program. This idea was shared in May 2010, and the spacecraft could have been launched between 2023 and 2025, depending on money and the type of engine used.

Another mission idea was part of the Discovery Program and was called Centaurus. If chosen, this mission could have launched between 2026 and 2029 to fly by Chiron and another similar object in the 2030s.