You may have heard of tropical-cyclone hurricanes, extreme weather events that batter coastal regions, or the Carolina Hurricanes, an NHL team that won the 2006 Stanley Cup. But now scientists have discovered a mind-boggling new type of hurricane that exists in the upper region of Earth’s atmosphere, where our planet’s skies meet outer space: a “space hurricane.”
The first observations of a space hurricane provide an amazing glimpse of a phenomenon that may be common on planets that host atmospheres and magnetic fields, according to a study published last week in Nature Communications. Formed on August 20, 2014, the space hurricane was similar in many ways to a regular tropical hurricane, except it emerged at a much higher altitude and rained down electrons instead of water.
While the study is focused on the inaugural observation of a space hurricane, which was spotted by the Defense Meteorological Satellite Program (DMSP), scientists have already discovered many more space hurricanes in DMSP data.
“There are tens of space hurricane events from the satellite, which has already been identified by our team, and I think there are more cases in the future and in the dataset that we didn’t finish,” said Qing-He Zhang, a space scientist at Shandong University who led the new research, in an email.
“I think there will be more teams from Europe, US, Canada, Japan and China, etc., who will do more research on space hurricanes in the future,” he added.
Prior to this discovery, Zhang and his research group had been pondering the possible existence of space hurricanes for years. The team’s research focus lies in the interactions between the ionosphere, an atmospheric layer that extends some 50 to 600 miles above Earth’s surface, and the magnetosphere, the region shaped by our planet’s protective magnetic field. At the poles, these interactions generate the magical and dazzling auroras that are popularly known as the Northern and Southern Lights.
Tropical hurricanes are driven in part by the movements of heavy air masses that generate strong winds; Zhang and his colleagues suspected a similar mechanism might be at work in the outer space environment close to Earth. In the case of space hurricanes, the solar wind, a stream of charged particles that flows from the Sun, slams into Earth’s upper atmosphere and transfers its energy into the ionosphere, driving the cyclone formation.
To glimpse this special form of hurricane for the first time, the team pored over more than a decade of observations captured by the four satellites in the DMSP.
“Actually, my student and I spent about two years to view thousands of aurora images observed by the DMSP satellites for [the most] recent 15 years, and found there are tens of cases showing the space hurricane features,” Zhang explained.
While many of these features were unclear, “of course, the one shown in our paper is the best,” he added.
Indeed, the August 2014 space hurricane was “a long-lasting, large, and energetic space hurricane” that produced an “auroral signature,” according to the study. Spinning in an anti-clockwise direction and sprouting spiral arms, the storm stretched across some 1,000 kilometers (621 miles) above Earth’s northern magnetic pole, persisting for nearly eight hours before it died down.
Instead of the air masses that make up tropical cyclones, space hurricanes are driven by plasma, an energized gas that is abundant in the inner magnetosphere. The upward thrust of intense magnetic currents stimulated the cyclone to precipitate electrons. Some of these electrons were accelerated to energies of about 10 kiloelectron volts, which is comparable to the power conferred by many particle accelerator facilities on Earth.
The observations offer an exciting look at a previously unknown type of space storm, but Zhang noted that the new study is only the beginning. The team hopes to follow up on this research by asking questions such as: What controls the rotation of space hurricanes? Are these space storms seasonal like their tropical counterparts, perhaps limited to the summer when the Earth’s magnetic dipole is tilted just the right way? And can space hurricanes be forecasted like weather events on Earth?
These questions are important not only to satisfy our scientific curiosity, but also because extreme space weather events can wreak havoc on satellite electronics, radar systems, and communications networks.
Future research into space hurricanes will also help scientists estimate the prevalence of space weather beyond our planet—and even beyond our galaxy—which can have implications for our understanding of alien worlds, and the lifeforms that may inhabit them.
“The space hurricane is likely a universal phenomenon, occurring at other magnetized bodies in the universe (planets and their moons, etc.),” the team concluded in the study. “The process may also be important for the interaction between interstellar winds and other solar systems throughout the universe.”