The Voyager 2 spacecraft camera captured Neptune and Triton together in crescent phase as it passed by in 1989. This picture of the gas giant and its cloudy moon was taken from behind the planet just after closest approach. It could not have been taken from Earth because Neptune never shows a crescent phase to sunward Earth; the sun always fully illuminates Neptune from our point of view. The unusual vantage point robs Neptune of its familiar blue color because the sunlight seen from behind the planet is scattered forward and is reddened like the setting Sun.
Image Credit: NASA/Voyager 2
This NIRCam image captures Neptune’s rings and seven of its 14 known moons: Galatea, Naiad, Thalassa, Despina, Proteus, Larissa, and Triton.
While Saturn has the best known set rings, all four of the gas giant planets have rings. Jupiter’s are quite simple and almost unnoticeable. The rings of Uranus are more extensive, but not as complex as Saturn’s. Neptune’s rings are simple, but more complex than Jupiter’s. This 591-second exposure of the rings of Neptune was taken by Voyager 2’s wide-angle camera.
Triton is Neptune’s largest moon. This photomosaic was assembled from images taken by Voyager 2 in 1987.
Neptune was discovered 175 years ago this week. This triptych of images show how the planet appeared to Voyager 2 during its flyby (left), to the Hubble Space Telescope (center), and to my backyard telescope (right—look closely, it’s really there).
It’s been 30 years since Voyager 2 did it’s last planetary flyby at Neptune. It took his picture less than five days before the spacecraft’s closest approach 25 August, 1989. The picture shows Neptune’s “Great Dark Spot”—a giant storm—and the bright clouds that follow the storm.
Neptune has seasons which drive some of the features in its atmosphere, but those seasons are much longer than on Earth, lasting for decades rather than months.
This new Hubble Space Telescope image reveals a new dark vortex in the atmosphere of Neptune. Neptune’s dark vortices are high-pressure systems and are usually accompanied by bright “companion clouds,” and the visible-light image on the left shows the dark feature near a patch of bright clouds in the planet’s southern hemisphere. The bright clouds form when the flow of the atmosphere is perturbed and diverted upward over the dark vortex, probably causing methane to freeze into ice crystals. The image at top right is a full-color close-up of the complex feature. The image at bottom right shows that the vortex as seen in blue wavelengths.