The photo at left is an enhanced-color image of Neptune from the Hubble Space Telescope. At the right, that image is combined ...

At the left, an enhanced-color image of Neptune from the ... and we expected to see the same on Neptune as we investigated the planet over the years with the best ground-based facilities available ...

Astronomers had observed auroras on all other planets in the Solar System, and spotting one in Neptune completes the list.

although scientists had long suspected the phenomenon occasionally occurs on the planet. At the left, an enhanced-color image of Neptune from NASA’s Hubble Space Telescope. At the right ...

"Neptune was the missing piece of the puzzle when it came to detecting auroras on the giant planets," said the European Space Agency.

The planet’s elusive aurorae are much colder than expected, which is how they evaded detection for so long.