Cassie Kelly | NASA | May 9, 2017
Here’s how a “normal” solar storm happens: Magnetic fields and plasma explode from within the sun’s corona, called a coronal mass ejection or CME. These ejections form red-hot patches on the surface of the sun and when they burst, they send waves of plasma across the solar system, causing what we describe as solar storms.
But, some storms, known as “stealth CMEs” are sneakier and have pretty much no warning signs.
Obviously uncomfortable by this, an international team of scientists tweaked their instruments until they could detect the subtle changes that signal a stealth CME.
The instruments used were NASA’s STEREO satellite, which tracks the flow of energy and matter from the sun to Earth, and the SOHO satellite, which studies the internal structure of the sun. Both instruments helped the team track magnetic lines that flow around the sun. Within those lines, they could actually see how a stealth CME unfolds.
Regular CMEs can erupt at 1800 miles per second, sending magnetic winds toward Earth and disrupting the electrically charged particles in the ionosphere, wiping out radio and satellite transmission during a solar storm. But the team found that winds from stealth CMEs burst at just 250 to 435 miles per second, which is not much faster than the steady stream of charged particles that constantly flow from the sun.
And although they seem weak, the magnetic structure of these stealth CMEs can pinch off bursts of plasma, causing quite a disruption. This process occurs when the magnetic lines are stressed by the sun’s rotation and cause the lines to coil with tension. After enough tension builds, the coils unhinge and form a massive bubble of plasma that floats away from the sun.
The threat of a solar storm, stealthy or not, always warrants more research, mostly because the true extent of a massive storm is unknown. Solar storms usually hit Earth every 100 years, and we are long overdue. The last big storm was the Carrington Event in 1859, before telephones were invented and electricity was a rarity. Still, the Carrington Event was strong enough for telegraphs to burst into flames. It’s no wonder there is a push to understand the sun’s hellish ways before it’s too late.