Scientists Find Surprise Atmosphere Beyond Pluto

Everyone’s favourite demoted planet, Pluto, may be shielding a mystery that’s baffled scientists.

An icy body beyond the dwarf planet seems to have an atmosphere that shouldn’t be there, according to a paper published in Nature Astronomy.

At just 500km across, the object, catchily named (612533) 2002 XV ought to be too tiny to have any atmosphere at all.

That’s partly why little planet Pluto was believed to be the only object in our solar system that had an atmosphere beyond Neptune.

But researchers hink they’ve found a “refractive signature, indicating a thin atmosphere” from the even tinier icy mass.

And they do mean “thin”. Some reports suggest the potential atmosphere could be 50-100 times thinner than Pluto’s own, already very weak, atmosphere, and 5-10 million times thinner than ours here on Earth.

Nonetheless, the minor “plutino” planet seemed to affect how a distant star looked while it occulted (temporarily appeared to cover) it.

Rather than cleanly appearing, being hidden, and then reappearing in a kind of “blink” or “wink” illusion, the star appeared to fade slowly as it approached and left the cover of the plutino. That usually only happens when a plant has an atmosphere, as the gases change how the light is filtered.

“This discovery suggests that the traditional idea that global dense atmospheres form only around larger planets must be revised,” the paper reads.

However, planetary scientist Alan Stern told the Associated Press that while “The implications are profound if verified,” the “amazing development… sorely needs independent verification”.

That could involve confirmation by, e.g., NASA’s Webb Space Telescope.

The researchers put forward two theories, though Space.com pointed out that both may have flaws.

The first suggests that another body, like a comet, might have impacted the plutino. But that’d be a stroke of luck on the researchers’ part: the gases from collisions like these fade over time, meaning we would have had to have caught it relatively soon after the impact.

That’s why, study author Ko Arimatsu told AP, the researchers plan to monitor the site. “If the atmosphere fades over the next several years, that would support an impact origin.”

Another theory? Ice volcanoes, which release sublimated gas through cryovolcanic activity. But the cause of this proposed activity is completely unknown.

“If [the atmosphere] persists, or varies seasonally, that would point more toward ongoing internal gas supply,” Arimatsu said.