For the first time this century, NASA scientists can confirm that a dark vortex has been spotted in Neptune’s atmosphere, as the new feature is clearly visible in images obtained last month by the Hubble Space Telescope, US space agency officials announced on Thursday.
While this isn’t the first time that something like this has been spotted around Neptune, as a dark vortex was detected twice previously (once by Voyager 2 in 1989, once by Hubble in 1994), these latest images verify that Jupiter is not the only planet in our solar system with its own spot.
In Neptune’s case, the dark vortices spotted by University of California at Berkeley astronomer Mike Wong and his colleagues are high pressure systems that are typically accompanied by what the researchers refer to as bright “companion clouds.” These clouds form as ambient air is forced over the vortex, causing its component gazes to freeze and form crystals of methane ice.
“Dark vortices coast through the atmosphere like huge, lens-shaped gaseous mountains,” Wong explained in a statement. “And the companion clouds are similar to so-called orographic clouds that appear as pancake-shaped features lingering over mountains on Earth.”
Credit: NASA
Dark vortices vary greatly in terms of size, shape, duration
Wong, along with a group of collaborators from Cal-Berkeley, the Outer Planet Atmospheres Legacy (OPAL) and elsewhere, discovered a dark feature located close to and slightly below a patch of bright clouds in an image of Neptune captured by Hubble in May. This high-pressure system, they noted, is best observed at blue wavelengths.
It was nearly one year ago, in July 2015, that several astronomers and observatories detected bright clouds in the distant planet’s atmosphere and began to wonder if they might be companion clouds associated with an unseen dark spot. That September, members of the OPAL program, a project that uses Hubble to compile annual global maps of the solar system’s outer planets, first spotted a dark vortex near where a group of clouds had been tracked from the ground.
The new Hubble images show that vortex a second time, confirming the OPAL team’s previous sighting and allowing them to create a higher-quality map of the feature and its surroundings, the agency said. Over the years, these dark vortices have been surprisingly diverse in regards to their sizes, shapes and durations, and the researchers hope that this new breakthrough will help reveal how they form, how they interact with the environment and how they ultimately dissipate.
“The results from Hubble confirm the Outer Planet Atmospheres Legacy program theory that Neptune’s spots are a sustaining feature,” Orlando Sentinel reporter Emilee Speck said, adding that the shape of the clouds are similar to those found above high peaks here on Earth.
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Image credit: NASA
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