Two decades worth of observations revealed unexpected cooling of the solar system’s most distant planet Neptune amid its astronomical summer.
Neptune is orbiting 30 times farther away from the sun than Earth with one year lasting 165 Earth years. The ice giant’s seasons, too, last much longer than those on Earth — more than 40 Earth-years each.
As the planet moved into its southern summer over the past two decades, astronomers observed its average global temperatures plummet by a staggering 14 degrees Fahrenheit (8 degrees Celsius).
“This change was unexpected,” Michael Roman, a postdoctoral research associate at the University of Leicester and lead author on the new paper, said in a statement. “Since we have been observing Neptune during its early southern summer, we would expect temperatures to be slowly growing warmer, not colder.”