Tiny World Beyond Pluto Shows Signs of Atmosphere, Surprising Scientists

Top Summary

• What happened: Astronomers observed an icy object beyond Pluto, 2002 XV93, displaying behavior consistent with having a thin atmosphere during a stellar occultation.
• Why it matters: This object, only 470 km wide, would be the smallest and most remote to host a gaseous layer, challenging theories on how such small bodies retain atmospheres.
• What changes: This discovery expands our understanding of the outer solar system and the potential for atmospheric presence on small, distant celestial bodies.
• Who is affected: Astronomers, planetary scientists, and the scientific community interested in the formation and evolution of the solar system.

Mysterious Atmosphere Beyond Pluto

A distant icy object located beyond Pluto, named 2002 XV93, may possess a thin atmosphere. This would make it the smallest and most remote known body in the outer solar system to potentially host a gaseous layer.

Until now, Pluto was the only trans-Neptunian object confirmed to have an atmosphere, making this new finding significant and drawing the attention of astronomers.

The Discovery Unfolds

The discovery was made by a research team led by astronomer Ko Arimatsu of the National Astronomical Observatory of Japan. They were monitoring 2002 XV93 with a network of telescopes.

On January 10, 2024, 2002 XV93 passed in front of a distant star, an event known as a stellar occultation. Such events allow scientists to study distant objects by analyzing how they affect starlight.

Instead of the star disappearing and reappearing abruptly, researchers observed its brightness fading and returning gradually over approximately 1.5 seconds. This behavior strongly suggests that the starlight passed through a thin layer surrounding the object, possibly an atmosphere.

Scientists estimate that if an atmosphere exists, its pressure is roughly one ten-millionth of Earth's atmospheric pressure.

Unraveling the Phenomenon

This finding surprised researchers because 2002 XV93 is only about 470 kilometers wide. Objects of this size are generally believed to have insufficient gravity to retain gases for extended periods.

Scientists propose several possibilities to explain this unexpected atmosphere. A recent collision with a comet-like body may have released gas into the surrounding space, temporarily creating the atmosphere.

Another theory suggests the object could be experiencing cryovolcanic activity, where icy materials erupt from beneath the surface and release gases.

However, many uncertainties remain. The current observations cannot determine the exact composition of the surrounding material, meaning it could consist of dust rather than gas. Researchers also lack information about the atmosphere's height and structure.

What to Watch Next

Future observations will be crucial in understanding this phenomenon. If the atmosphere gradually disappears, it may indicate a temporary cloud created by an impact event. If it persists or changes over time, it could point to ongoing geological activity on this distant world.