Astronomers discover Great Cold Spot on Jupiter

Astronomers have discovered a massive aurorae-generated weather system, dubbed the Great Cold Spot, on Jupiter. Comparable in scale to the planet’s famous Great Red Spot, the phenomenon may have existed for thousands of years and is the first direct evidence of a sustained weather system generated by polar aurorae, opening the possibility of similar phenomena on other planets.

Observed by University of Leicester astronomers as a localised dark spot that is up to 24,000km tall and 12,000km wide, the spot is located in the planet’s thin high-altitude thermosphere. It is thought to bearound 200 Kelvin cooler than the surrounding atmosphere, which has a temperature range of between 700K (426°C) and 1000K (726°C).

“This is the first time any weather feature in Jupiter’s upper atmosphere has been observed away from the planet’s bright aurorae,” said study lead author Dr Tom Stallard, associate professor in Planetary Astronomy at the University of Leicester.

“The Great Cold Spot is much more volatile than the slowly changing Great Red Spot, changing dramatically in shape and size over only a few days and weeks, but it has re-appeared for as long as we have data to search for it, for over 15 years.  That suggests that it continually reforms itself, and as a result it might be as old as the aurorae that form it – perhaps many thousands of years old.”

The phenomenon is thought to be caused by the magnetic field of the planet, with Jupiter’s polar aurorae pushing energy into the atmosphere in the form of heat flowing around the planet. This push creates a cooling region in the thermosphere; the boundary layer between the underlying atmosphere and the vacuum of space.

The Great Cold Spot was found by using the CRIRES instrument on the Very Large Telescope (VLT) to observe spectral emissions of H3+, an ion of hydrogen present in large amounts in Jupiter’s atmosphere.  With the ion observed, the astronomers were able to map the mean temperature and density of the planet’s atmosphere.

The team was then able to compare its map to images of H3+ emission from Jupiter’s ionosphere taken by NASA’s InfraRed Telescope Facility from 1995 to 2000. By combining images taken over set periods of time, including over 13,000 images taken over more than 40 nights by the InfraRed Telescope Facility, the team was able to find the Cold Spot as a dark area in Jupiter’s hot upper atmosphere.

The changing shape of the newly discovered Great Cold Spot, as observed over time. Image courtesy of the University of Leicester. Featured image courtesy of NASA

“What is surprising at Jupiter is that, unlike weather systems on Earth, the Great Cold Spot has been observed at the same place across 15 years. That makes it more comparable to weather systems in Jupiter’s lower atmosphere, like the Great Red Spot,” added Stallard, who is funded by the Science and Technology Facilities Council.

“Observations and modelling of Earth’s upper atmosphere have shown that, on the short term, there may be changes in the temperature and density of the upper atmosphere.”

The team now hopes to use what was learnt of the Cold Spot to search for other such features that may be hidden in the gas giant’s atmosphere.

The study, which is published in Geophysical Research Letters, is available in full online.

NASA astronaut Peggy Whitson to smash US cumulative space record

Peggy Whitson, a NASA astronaut currently onboard the International Space Station, is set to break the United States record for cumulative days in space within weeks. However, her record will now be far harder to beat after the space agency decided to extend her stay on the ISS by three months.

Whitson had been scheduled to return to Earth as part of Expedition 51, which would have seen her arrive back on the Blue Marble in June, having broken the cumulative space record on 24th April. However, the extended stay will now see her return as part of Expedition 52, with a scheduled return in September.

“This is great news,” Whitson said, speaking from the ISS. “I love being up here. Living and working aboard the space station is where I feel like I make the greatest contribution, so I am constantly trying to squeeze every drop out of my time here. Having three more months to squeeze is just what I would wish for.”

The United States record for cumulative days in space is currently held by Jeff Williams, who has racked up a total of 534 days over four space flights. When Whitson completes her current mission she will have totalled over 600 days.

However, she will still have some way to go to break the overall record, which is held by Roscosmos cosmonaut Gennady Padalka with a total of 879 days in space over 5 missions. But with this being only Whitson’s third time in space, it is always possible that NASA could send her back to the ISS in the future, particularly as she is considered one of the most senior astronauts currently active within the agency.

“Peggy’s skill and experience makes her an incredible asset aboard the space station,” said Kirk Shireman, NASA’s International Space Station Program Manager, in comments about the decision to continue her stay aboard the ISS. “By extending the stay of one of NASA’s most veteran astronauts, our research, our technology development, our commercial and our international partner communities will all benefit.”

Images courtesy of NASA Johnson

Whitson first went into space on Expedition 5 back in 2002, having been selected as an astronaut candidate by NASA in 1996 following a stint as a project scientist for the Shuttle-Mir programme.

Since then she has become one of the most successful female astronauts of all time, and in 2008 was made the first female commander of the ISS, before going on to become the first woman to command it twice.

She is also no stranger to record-breaking. She has already spent more cumulative days in space than any other woman, and has completed the most spacewalks of any female, beating Sunita Williams’ record on her second mission.