A mysterious 'Rosetta Stone' explosion reveals a missing link behind solar eruptions

A mysterious 'Rosetta Stone' explosion reveals a missing link behind solar eruptions
The failed portion of a solar eruption on March 13, 2016.NASA/Solar Dynamics Observatory
  • Scientists recently examined a solar eruption from 2016 that seemed to defy categorization.
  • They named it the "Rosetta Stone" since it connected three different types of eruptions.
  • Their research now suggests that all three forms of solar eruptions may have the same origin.

When the sun isn't sleeping, it's bursting with activity - including giant solar eruptions.

These eruptions usually take a few forms: The most violent ones are either narrow beams of solar material, known as jets, or large bubbles of that same material known as coronal mass ejections. Other times, bursts of energy and solar particles fail to launch all the way into space, then fall back down toward the sun. That's called a partial eruption.
But in March 2016, NASA scientists detected an eruption that didn't neatly fit these categories: The sun spewed a hot layer of solar material that was too big for a jet, but too narrow for a coronal mass ejection. A half-hour later, a partial eruption emerged from the same location, blasting cooler plasma that ultimately collapsed on itself.
New research presented at the American Astronomical Society this week dubbed the event a "Rosetta Stone" eruption since it connected all three forms of solar eruptions - and even suggested they might have the same origin.

"This event is a missing link, where we can see all of these aspects of different types of eruptions in one neat little package," Emily Mason, a solar scientist at NASA's Goddard Space Flight Center, said in a statement. "It drives home the point that these eruptions are caused by the same mechanism, just at different scales."

Scientists now suspect that solar eruptions exist on a spectrum, with jets on one end and coronal mass ejections on the other. But they haven't figured out the underlying mechanism that drives these eruptions - or why certain eruptions take one form over another.

The new research could bring them closer to an answer. Eventually, scientists may even be able to more accurately predict when a large solar eruption is headed toward Earth.

Scientists are still puzzled by the 'failed' eruption

A mysterious 'Rosetta Stone' explosion reveals a missing link behind solar eruptions
A coronal mass ejection as seen from NASA's Solar Terrestrial Relations Observatory-A spacecraft.NASA/STEREO/COR2
The conditions behind a solar eruption build up over several days or weeks. As the sun rotates, its magnetic field lines become twisted and tangled. When two oppositely-charged magnetic fields move apart, the field lines that connect them stretch out like a rubber band. In the process, they accumulate energy and fill up with plasma. All that energy and particles then gets released as magnetic fields break and reconnect.

This ultimately results in an eruption, though scientists still haven't identified an obvious trigger.

In the case of the "Rosetta Stone" eruption, scientists first spotted an active region - an area of intense magnetic activity that can give rise to solar eruptions - in January 2016.

The actual eruption took place less than two months later, when a dome of hot plasma lifted off, producing a crossover between a jet and a coronal mass ejection. A ring of cooler plasma underneath seemed like it would erupt as well, but it rose and fell back down like "cars on a roller coaster track," Mason told the Universities Space Research Association.
A mysterious 'Rosetta Stone' explosion reveals a missing link behind solar eruptions
A photo of a huge, handle-shaped prominence erupting from the sun, taken on September 14, 1999.ESA/NASA/SOHO

That partial, or "failed," eruption was puzzling to scientists, so Mason's team is now searching for more clues through computer models.

Finding out what triggers an eruption, or why certain eruptions fail, could help scientists identify solar storms several hours before they approach our planet. Right now, scientists are only able to reliably predict space weather about an hour in advance.

That's not much of a warning, considering that the most intense solar storms can interfere with spacecraft technology and make it harder for astronauts to communicate with mission control.
Solar storms can also down power grids or satellite communications. In 2017, for instance, two solar storms cut off emergency radio communications in the immediate wake of Hurricane Irma - one of the most powerful Atlantic hurricanes on record.