A small icy world more than 5.5 billion kilometers from Sol has gained prominence in astronomy. The trans-Neptunian object (612533) 2002 XV93, about 500 kilometers in diameter, has a thin and delicate atmosphere. The detection occurred through stellar occultation observations carried out by a team from Observatório Astronômico Nacional of Japão.

The finding is surprising because bodies this size and so far away usually lose any gas quickly into space. The object is a plutino, a body that orbits in 2:3 resonance with Netuno, like Plutão. The discovery opens new questions about the small-object activity of Cinturão and Kuiper.

Stellar Ocultação enabled indirect detection

Astrônomos used three telescopes on Japão to record the moment the object passed in front of a distant star. The star’s light gradually dimmed, rather than disappearing abruptly. Esse profile indicates refraction caused by a layer of gas surrounding the celestial body.

The estimated surface pressure is between 100 and 200 nanobars. Isso represents 5 to 10 million times less density than the Earth’s atmosphere at sea level and 50 to 100 times less than Plutão. The data came from professional observatories and a telescope operated by an amateur astronomer.

More on this story: National Astronomical Observatory of Japan finds atmosphere on body smaller than Pluto 2002XV93

• Medição occurred in 2024 during a rare alignment event.
• Três observation sites confirmed the same signal.
• Mudança smooth in brightness lasted about 1.5 seconds.
• Modelo indicates gases such as methane, nitrogen or carbon monoxide.

Corpo too small to retain air according to older models

Cientistas considered that objects less than about a thousand kilometers in diameter would not be able to hold onto an atmosphere because of weak gravity. Mercúrio, Lua and Ceres do not have one. The 2002 XV93 breaks this expectation by demonstrating retention even with a diameter equivalent to a third of that of Ceres.

Sol’s distance makes the environment extremely cold, which helps keep volatile substances frozen to the surface. Ainda so the atmospheric exhaust should be fast. Cálculos show that the current layer would last less than a thousand years without constant replacement.

Origem from the atmosphere still generates debate

Duas main hypotheses explain the phenomenon. One points to cryovolcanism, with the release of ice gases from inside the body. The other suggests a recent comet impact that vaporized material and created a temporary cloud. Future Observações should distinguish between the two.

Ko Arimatsu, leader of the study, highlighted that the result changes the view on small worlds in Sistema Solar. Ele coordinates the work published in the journal Nature Astronomy on May 4, 2026. The researcher stated that the finding indicates that these objects may not be as inert as previously thought.

Implicações for Cinturão study of Kuiper

Cinturão of Kuiper houses thousands of icy objects left over from the formation of Sistema Solar. Até now, only Plutão had confirmed atmosphere between them. The new detection suggests that other similar bodies may have internal activity or undergo periodic impacts.

Telescópios like James Webb can analyze the exact composition of the atmosphere in future observations. Continuous Monitoramento of the object will help verify whether the layer persists, varies with the seasons, or dissipates. Isso will reveal whether the gas supply is continuous or spot.

Learn more: Icy planet from the outer reaches of the Solar System reveals unexpected atmosphere

Detalhes orbitals and object classification

The 2002 XV93 completes two laps around Sol in the time it takes Netuno to do three. Sua’s orbit is about 39.6 astronomical units on average. At the time of observation, it was more than 5.5 billion kilometers away from Terra. The surface likely consists of water ice, methane and other volatile compounds.

Classification as plutino places it in a stable dynamic group. Esses bodies share characteristics with Plutão, but on a smaller scale. The diameter of 500 km makes it the smallest object known so far with a global atmosphere detected by gravity.

The study involved collaboration between professional and amateur astronomers. The observation network on Japão allowed us to capture the transient event accurately. Resultados reinforce the importance of monitoring stellar occultations to investigate distant objects that cannot be imaged directly.