Neptune Has Been Slowly Cooling For 15 Years When It Should Be Warming

Summer on Neptune seems to be cooling down. Observations dating back to 2003 show that the temperature in the planet's southern hemisphere has been dropping, despite the fact that these measurements were taken in the early part of its long summer. New Scientist reports: Michael Roman at the University of Leicester, UK, and his colleagues examined data from several of the world's biggest telescopes to figure out how the temperature of Neptune has changed since the first relatively detailed measurements were made in 2003. "Because we are observing Neptune in this southern summer, we basically expect temperatures to be getting slowly warmer in time," says Roman. "But what we saw was that they dropped by about 8C" over the course of 15 years, he says. The observations also revealed a surprise near the planet's south pole. Between 2018 and 2020, an area there warmed by about 11C, an unexpectedly rapid change given that it takes Neptune more than 165 Earth years to complete a circuit around the sun. "A season on Neptune is over 40 years long, so we'd expect these changes to be a lot more gradual," says Roman.

Read more of this story at Slashdot.