An active sunspot on the sun that's turning away from Earth unleashed a powerful parting shot as it moved out of view on Saturday (April 30).
The sunspot AR2994, short for Active Region 2994, fired off a massive solar flare that registered as an X1.1-class solar storm. (X-class solar flares are the most powerful explosions on the sun.) NASA's Solar Dynamics Observatory captured stunning video of the solar flare in different wavelengths of light.
"Even with the sunspot completely hidden behind the sun's northwestern limb, the explosion still produced enough radiation for a strong shortwave radio blackout over the mid-Atlantic Ocean and much of Europe," astronomer Tony Phillips wrote on his website Spaceweather.com, which tracks solar flares. It lasted about an hour, he added.
The solar storm began at 9:37 a.m. EDT (1337 GMT) and reached peak strength 10 minutes later, according a NOAA alert from the Space Weather Prediction Group. The flare occurred ahead of a partial solar eclipse on Saturday, the first solar eclipse of 2022. The moon was expected to block out part of the sun for observers in parts of South America, the southern Pacific Ocean and Antarctica. Here's what time the solar eclipse of April 30 begins.
The solar eruption almost certainly fired off an intense coronal mass ejection, or CME, of charged particles, Phillips wrote. But because the flare came from a sunspot hidden from direct view from Earth, it likely won't hit Earth, he added.
Solar storms that erupt from the sun come in different strengths, or classes, used by scientists to determine their severity. The weakest solar flares are A-class, B-class and C-class events, with the more powerful M-class storms strong enough to amplify Earth's northern lights when they hit our planet.
X-class solar flares the strongest eruptions the sun experiences. When aimed directly at Earth, the most powerful X-class storms can pose a risk to satellites and astronauts, as well as interfere with power stations and radio signals on the surface. Each class of solar flare has nine divisions of intensity with the exception of X-flares. The biggest known X-flare was in 2003 and reached X28 before it overwhelmed the sensors monitoring it.
The sun has an 11-year space weather cycle, with the current cycle known as Solar Cycle 25 (it began in 2019). The sun is currently in an increasingly active phase of the cycle. It is being monitored by NASA's Solar Dynamics Observatory, the joint U.S.-European Solar and Heliospheric Observatory (SOHO) and other spacecraft.