A celestial event last week is helping astronomers from Lowell Observatory in Flagstaff study Pluto’s atmosphere. The ground-based data gives a clearer picture of the ninth classical planet.
The event is called an occultation, when a planet passes in front of a distant star. That’s what Pluto did last week. Astronomers tracked Pluto’s position from telescopes in Flagstaff and then watched the event from SOFIA, an airborne observatory.
Amanda Bosh is a planetary scientist at Lowell Observatory. “During this event, we watch the light from the star, and how it is extinguished as Pluto passes in front of it,” she said.
The way the light disappears and returns gives clues to the nature of Pluto’s atmosphere. Bosh says the most important discovery so far is that the atmosphere is still there. “And that sound kind of silly but Pluto has an eccentric orbit around the Sun. Right now it’s moving away from the sun, so basically what’s happening on Pluto is that it’s getting day by day a little bit colder.”
Scientists wondered if the atmosphere would be completely frozen, but the occultation experiment proved it’s not.
That will be useful information for NASA’s New Horizons mission. Next week the spacecraft will give the world its closest look yet at Pluto, which was discovered in 1930 by an astronomer at Lowell Observatory.
