When Pluto passed in front of a star on the night of August 15, 2018, astronomers deployed telescopes at numerous sites in the U.S. and Mexico to observe Pluto’s atmosphere as it was briefly backlit by the well-placed star. Scientists used this occultation event to measure the overall abundance of Pluto’s tenuous atmosphere and found compelling evidence that it is beginning to disappear, refreezing back onto its surface as it moves farther away from the Sun.