Strange Object Trapped Between Saturn and Uranus

A strange object that comes close to the sun, practically touches Saturn, and then moves farther away again even beyond Uranus has been found in space.

Called Minor Planet 2060 Chiron, it is a Centaur. Centaurs are like comets that are trapped, and they move in loops between Jupiter and Neptune.

First instance of Chiron passing before a star

Chiron is quite small at about only 218 kilometers (135 miles) wide, and sometimes it acts like a comet with bursts of activity. Surprisingly, no spaceship has ever visited one of these Centaurs.

In 2011, Chiron passed before a dim star when seen from Earth. This event is called a “stellar occultation.” Scientists determined the shape and size of Chiron by watching how it blocked the star’s light.

During this 2011 event, they witnessed something interesting. The star’s light dimmed not once but twice before Chiron covered it and then two more times after Chiron passed. This led scientists to believe that Chiron has a special disk of dust around it that can change shape and even imitate rings.

Opportunity seized to observe Chiron in 2018

On November 28, 2018, Chiron passed before another star. This time, Amanda Sickafoose, a top scientist at the Planetary Science Institute in Tucson, Arizona, seized the opportunity. Chiron’s shadow, created by the star, is especially small and can only be seen from a small part of the Earth, specifically southern Africa.

Sickafoose led a team that used a 1.9-meter (6.2 feet) telescope at the South African Astronomical Observatory in Sutherland, South Africa to watch this rare event.

Their findings, published exactly five years later, reveal a slightly different tale compared to what we learned in 2011. “We detected dips in the starlight as it was blocked by Chiron’s nucleus as well as by material located between 300 to 400 kilometers on either side,” Sickafoose said.

Observations from the movement of Chiron in 2018

As Chiron moved across the star, Sickafoose’s team noticed drops in the starlight caused by dust at distances of 352, 344, and 316 kilometers (around 219, 214, and 196 miles) from the center of Chiron.

Simply put, this material was about 100 to 130 kilometers (60 to 80 miles) above the surface of the Centaur. Once Chiron moved away from the star, two more drops were observed at 357 and 364 kilometers (221 and 226 miles) from Chiron’s center.

If Chiron had only two steady rings, we would expect just two sets of matching drops in light on both sides of Chiron. However, the unexpected third drop on one side of the Centaur suggests that things are a bit more complicated.

The South African Astronomical Observatory's 1.9-metre telescope has just revealed evolving material, not rings, circling Centaur (2060) Chiron; challenging previous interpretations of Chiron's structure, indicating dynamic changes rather than a stable two-ring system. 🪐 pic.twitter.com/JyVRKEGgbS

— SAAO (@SAAO) December 5, 2023

Additionally, the drops caused by this mysterious material occurred away from where the rings were located in 2011, although this was still within the measurement error of the 2011 observations. Aside from this, the size of the drops in starlight caused by the material was also different.

Sickafoose explained, “The locations and amounts of material that were detected around Chiron are different enough from previous observations to suggest that there is not a stable ring system but rather surrounding material that is currently evolving.”

Occultation of Chiron in 2022

Chiron once more passed in front of another star on December 15, 2022. This time, a team led by Jose Luis Ortiz from the Instituto de Astrofísica de Andalucía in Spain observed the event at the Kottamia Astronomical Observatory in Egypt.

What they saw was a change in the material around Chiron. They identified three balanced structures on both sides of Chiron. Two of these structures are thin, while one is wide. Together, they appear to make up a broad disk that spans 580 kilometers (360 miles) in width.

The material surrounding Chiron remains a mystery in terms of its origin and composition. However, there’s a good chance it originated from Chiron itself, possibly being ejected outwards during cometary outbursts.

This theory gained traction after Chiron was observed getting brighter by a magnitude of 0.6 during the summer of 2021. To put this into perspective, a magnitude 0 object is 100 times brighter than a magnitude 5 object on this brightness scale.