As if being distant and frigid weren't enough, Pluto is cloaked in a puffy atmosphere that contains highly toxic carbon monoxide, new data confirms. Observations of the dwarf planet made more than a decade ago offered inconclusive evidence of carbon monoxide in Pluto's atmosphere. The new study—based on data from the James Clerk Maxwell Telescope in Hawaii—not only confirms the gas is there, it shows that the amount of carbon monoxide has doubled since 2000.
In general, Pluto's atmosphere is very thin—about a millionth the atmospheric pressure of Earth's—but it extends relatively far into space. The solid part of the planet is just 1,430 miles wide. The new study shows that Pluto's atmosphere has grown over the past decade from a height of about 62 miles to more than 1,864 miles—a quarter of the distance to Pluto's largest moon, Charon. The astronomers think the increase may be due to Pluto's extreme seasons.