An active sunspot on the receding sun from Earth unleashed a powerful parting shot as it disappeared from sight on Saturday (April 30).
Sunspot AR2994, short for Active Region 2994, fired off a massive solar flare that was recorded 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 extreme northwest corner, the explosion 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 full strength 10 minutes later, according to an alert from NOAA’s Space Weather Prediction Group. The flare occurred before 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 April 30 solar eclipse begins.
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The solar flare almost certainly triggered an intense coronal mass ejection, or CME, of charged particles, Phillips wrote. But because the flare came from a sunspot hidden from Earth’s direct view, it likely won’t hit Earth, he added.
Solar storms that erupt from the sun have different intensities, or classes, used by scientists to determine their severity. The weakest solar flares are class A, class B, and class C events, with the most powerful class M storms being strong enough to amplify Earth’s northern lights when they hit our planet.
X-class solar flares are the strongest flares the sun experiences. When heading directly for Earth, the most powerful X-class storms can pose a risk to satellites and astronauts, as well as interfere with power plants and radio signals on the surface. Each class of solar flare has nine intensity divisions with the exception of X-flares. The largest 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 (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 US-European Solar and Heliospheric Observatory (SOHO), and other spacecraft.