Neptune: first dark vortex for 21st century discovered

NASA’s Hubble Space Telescope has confirmed the presence of dark vortex on Neptune. The high-pressure system has been identified for the first time on Neptune in the 21st century. Astronomers came to know about the presence from bright clouds.

Astronomer Mike Wong, of the University of California at Berkeley, explained that dark vortices move through the atmosphere as massive, lens-shaped gaseous mountains. It also carries clouds that are akin to organic clouds that are in the shape of pancakes.

Since July 2015, astronomers have been witnessing the clouds on Neptune. Originally, Hubble’s Outer Planet Atmospheres Legacy (OPAL) project was formed to

come up with global maps of the outer residents of the solar system each year. In September 2015, the researchers turned the OPAL towards Neptune.

The researchers then assessed OPAL’s map to find a dark spot near the bright spots. On May 16, 2016, astronomers again looked at Neptune with Hubble. The newly found vortex is around 3,000 miles across and is present on the planet’s southern hemisphere.

In the past, Voyager 2 and Hubble have unveiled about similar features on the ice giant. But this one is said to be the first one to be spotted in more than two decades. Earlier as well, there have been many dark vortices that have been seen in different sizes and shapes.

In comparison with storms on Jupiter, dark vortices on Neptune occasionally speed up or slow down and also, their timescales are shorter. Joshua Tollefson, a collaborator on the work, said that efforts are being made to better understand as to how these vortices are formed, how they move around the planet, how they interact with their environments and as to how they fall apart.

Details about the new vortex will certainly help astronomers to better understand Neptune’s atmosphere and vortices. Announcement about the new feature was made through a Central Bureau for Astronomical Telegrams (CBAT) electronic telegram.

Over the years, Neptune’s dark vortices have shown a great diversity when it comes to size, shape and stability. Neptune’s dark vortices are generally seen at blue wavelengths and only Hubble has the required resolution power to see vortices on distant Neptune.

In 1989 and 1994, similar dark spots were witnessed on Neptune, announced NASA. In 1989, it was spotted through the Voyager 2 and in 1994 via the Hubble Telescope. It was in 1989 when the most famous discovery of dark spot was made on Neptune. It was known as the Great Dark Spot that was located in Neptune’s southern atmosphere and is around as large as earth. But it is the latest one to be observed on the planet in the 21st century.

“When NASA’s Voyager 2 spacecraft flew by Neptune in 1989, astronomers were surprised to see such a gaping, dark hole at southern latitudes in the giant planet’s cyan-colored atmosphere”, said the researchers, who also mentioned that the dark spot later disappeared. Dark vortices are formed in Neptune when clouds of air and gas swirl up and freeze up resulted into a solid single mass that moves on the planet’s atmosphere.

According to a report in Weather News by Eric Zerkel, “NASA just spotted a huge dark spot on Neptune for the first time this century, and it’s roughly the size of the United States. Features of this dark spot, aptly called a dark vortex, were first detected in July 2015, but it wasn’t until NASA turned its Hubble Telescope toward the planet in May 2016 that the full extent of the feature was revealed.”

Astronomers previously captured proof of dark vortices on Neptune in 1989 and 1994, but the latest edition is the highest quality yet. The newly released images are all a part of Hubble’s Outer Planet Atmospheres Legacy (OPAL) project, aimed at documenting and explaining activity on the most distant planets in our solar system.

A report published in the USA Today News said, “Move over Jupiter, now Neptune has a spot, too. Scientists using the Hubble Space Telescope last month noticed a dark vortex in the distant planet’s atmosphere. Neptune’s dark spots or vortices are high-pressure systems and are usually accompanied by bright “companion clouds,” which are also now visible.”

Neptune’s dark vortices tend to meander around and sometimes seem to speed up or slow down, NASA said. They also come and go on much shorter time scales, when compared to similar spots seen on Jupiter. Large storms on Jupiter, such as the planet’s famed red spot, evolve over decades. NASA announced that similar dark spots were spotted on Neptune in 1989 and in 1994, but this vortex is the first one observed there in the 21st century.

“Beginning in July 2015, bright clouds were again seen on Neptune by several observers, from amateurs to astronomers at the W. M. Keck Observatory in Hawaii. Astronomers suspected that these clouds might be bright companion clouds following an unseen dark vortex. Neptune’s dark vortices are typically only seen at blue wavelengths, and only Hubble has the high resolution required for seeing them on distant Neptune,” according to a news report published by Science Daily.

Planetary astronomers hope to better understand how dark vortices originate, what controls their drifts and oscillations, how they interact with the environment, and how they eventually dissipate, according to UC Berkeley doctoral student Joshua Tollefson, who was recently awarded a prestigious NASA Earth and Space Science Fellowship to study Neptune’s atmosphere. Measuring the evolution of the new dark vortex will extend knowledge of both the dark vortices themselves, as well as the structure and dynamics of the surrounding atmosphere.

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