Dark storm on Neptune’s astronauts baffles after surviving migration to equator

A dark storm of 4,600 miles across the distant ice giant Neptune has confused astronauts after changing its course, never seen before.

Storm vortices like Neptune’s dark place are unusual, but no one has ever seen them turn back towards the poles after migrating to the equator.

Using images from the Hubble Space Telescope, University of California, Berkeley astronomers said the change of direction was ‘invisible’ and surprising.

The storm is wider than the Atlantic Ocean on Earth and was first discovered by Hubble in 2018 where he was born in the northern hemisphere of Neptune.

A year after it was first seen it had begun to move towards the equator, but the latest observations from August 2020 show that it is moving back north.

Hubble has discovered similar dark places over the past 30 years but this ‘invisible atmospheric transport’ is something astronauts have never seen.

This major storm was not alone, according to the UC team. Images captured by Hubble in January 2020 revealed a small dark-like spot on Neptune.

It did not last long and was probably part of the great storm that broke and spread – as it had not been seen in follow-up studies since August.

‘We are excited about these ideas because this smaller dark fragment may be part of a dark space chaos process,’ said author Michael H. Wong.

‘This is a process that has never been seen before. We saw other dark spots disappear, and they are gone, but we did not see anything disturbing it, even as would be expected in computer simulations. ‘

The storm is 4,600 miles across and is the fourth darkest place Hubble has seen on Neptune since the ice giant was first spotted in 1993.

Voyager 2 – the spacecraft now outside the solar system in intercellular space – witnessed two dark storms in 1989 when it flew with the distant world.

These ‘dark vortices’ are high pressure systems that can be at the center of latitudes and can move into the equator on the blue planet.

They start to stabilize – due to Coriolis forces causing north hemisphere storms to rotate clockwise – but as it moves toward the equator this effect will be felt. becomes weaker and the storm subsides.

Computer simulations suggested that these storms would follow a relatively straight path to the equator so that there would be no Coriolis effect to hold them together.

However, comments from Hubble showed that this did not happen, in fact, as the dark spot approached the equator it began to turn back towards the pole region.

“It was very interesting to see this one act as it should be and then suddenly it just stops and turns back,” said Wong. ‘That was a surprise.’

It is not known for sure why the dark spot survived in the equatorial killing zone, but Wong believes this may be related to the smaller dark spot seen in the images.

He called it ‘Dark Spot Jr’ – it was about 3,900 miles across and near the side of the main equator – where symbols were expected to fall apart. .

‘When I first saw the small space, I thought the big one was annoying,’ Wong wrote in a blog post for NASA.

‘I didn’t think another fortune was creating because the little one is further towards the equator. So it is within this unstable area. But we cannot prove a connection between the two. It remains a complete mystery.

‘It was also in January that the dark fortune halted its movement and it began to move north again,’ said Wong.

‘Perhaps peeling that crumb was enough to stop it moving towards the equator.’

Another unusual feature of this dark place is that it is not surrounded by a lighter set of bright companion clouds – which were visible in the 2018 Hubble images.

These clouds form when airflow is blown and moved up above the vortex and cause gases to freeze into methane ice crystals.

Astronomers are planning a more spectacular study of this phenomenon in the hope that it could reveal information on how the dark spots first change.

This will not solve the greater mystery of how these major storms form on the ice giant, but this latest location is the closest study to date thanks to Hubble.

‘We wouldn’t know anything about these latest dark spots if it weren’t for Hubble,’ wrote Amy Simon of NASA Goddard Space Flight Center.

‘We can now follow the great storm for years and look at its entire life cycle. If we didn’t have Hubble, we might think that the Great Dark Spot that Voyager saw in 1989 is still in Neptune, just like Jupiter’s Red Spot.

‘And, we wouldn’t know about the other four places Hubble discovered.’

The team’s research was presented at the Fall 2020 Meeting of the American Geophysical Union.