Astronomers discover unexpected atmosphere beyond Pluto on tiny solar system object

Astronomers have detected a thin yet rare atmosphere for the very first time beyond Pluto around a small celestial body in the outer solar system.

The existence of an atmosphere surrounding the tiny icy rock has baffled the researchers as earlier they did not previously think about the possibility of rock harboring atmosphere due to its really small size.

These icy and rocky bodies are called trans-Neptunian objects or TNOs which exist in the Kuiper belt bordering our solar system. These rocks are the remnants from its formation 4.5 billion years ago.

2002 XV93 icy rock

The icy rock in question, known as 2002 XV93, is a small TNO roughly 311 miles in diameter, significantly smaller than Pluto (1,477 miles).

By using a method called stellar occultation, researchers observed the object passing in front of a distant star. Instead of the star’s light blinking out immediately, it faded and reappeared gradually, showing the presence of a thin atmosphere responsible for bending the light.

“The observation data showed a smooth change of the star’s brightness near the edge of the shadow, lasting about 1.5 seconds. This kind of smooth brightness change is naturally explained if the starlight was bent by a very thin atmosphere around the object,” said Dr. Ko Arimatsu, associate professor and senior lecturer at the National Astronomical Observatory of Japan.

Talking about atmosphere density, it is estimated to be 5-10 million times thinner than Earth’s.

Possible origin

According to researchers, two possible theories could justify the existence of a rarely seen atmosphere possessed by such a small body.

The first theory is based on cyclovolcanism. The atmosphere could be the product of the release of internal gases like methane, nitrogen, or CO from beneath the icy surface through ice volcanoes.

In addition to this, a collision with another Kuiper Belt object could also lead to release of subsurface gases, thereby creating a temporary atmosphere.

The findings published in the journal Nature Astronomy are significant as if confirmed they can challenge the status quo related to small worlds.

The discovery also proves that even smaller objects in the Kuiper Belt can harbour an atmosphere, showing active geological activity in the outer solar system.

The discovery proves that even small objects in the Kuiper Belt can maintain atmospheres, suggesting the outer solar system is more geologically active than previously thought.

Future plans

To explore its true origin and nature, astronomers plan to use the James Webb Space Telescope to identify the atmosphere's chemical composition and monitor its pressure.

Dr. Scott S. Sheppard, staff scientist at the Carnegie Institution for Science in Washington, DC, said, “This shows the Kuiper Belt is not a cold dead place, but is teeming with activity and has many of the building blocks for life.”