Dynamic Atmosphere of Neptune

The two major planets beyond Saturn have only been visited once by a spacecraft, albeit briefly. NASA's Voyager 2 spacecraft swung by Neptune in 1989. Our robotic deep-space tourist snapped the only close-up, detailed images of these monstrous worlds. For Neptune, the images revealed a planet with a dynamic atmosphere with two mysterious dark vortices. But these views were only brief snapshots. They couldn't capture how the planets' atmospheres change over time, any more than a single snapshot of Earth could tell meteorologists about weather behavior. And, they go through protracted seasonal changes in their multi-decades-long orbits. Ever since the Voyager encounter, the Hubble Space Telescope has provided an opportunity to monitor these worlds like a diligent weatherman. Since Hubble's launch in 1990, astronomers have used it to amass an album of outer planet images. Yearly monitoring of these giant worlds is now allowing astronomers to study long-term seasonal changes, as well as capture transitory weather patterns. One such elusive event is yet another dark storm on Neptune, shown in this Hubble image of the planet.