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A moderately large solar flare was emitted by the sun Thursday, causing disruption to shortwave radios around North America and expelling a wave of slower particles that could strike our atmosphere in a colorful way this weekend.
SpaceWeather.com reports that the sunspot known as AR2371 fired off an M3-class explosion — a medium-size disturbance that was registered by the sun-watching sensors on the Solar and Heliospheric Observatory. Close-ups of the sunspot are collected here.
You can also see the flare in an extreme ultraviolet image from NASA's Solar Dynamics Observatory. The electromagnetic blast from the flare swept past Earth within only a few minutes. But events like this also create waves of charged particles that travel much more slowly than the speed of light.
Such bursts are known as coronal mass ejections or CMEs. If a strong CME makes a direct hit on Earth's magnetosphere, the blast can disrupt satellite operations and power grids. But Thursday's CME wasn't that strong, and it's expected to deliver merely a glancing blow to Earth.
The most noticeable effect will probably come in the form of brighter auroral displays at high latitudes, just in time for Sunday's solstice. If you're in the aurora zone, watch the skies. If not, watch SpaceWeather.com's aurora photo gallery.
More flares are expected from sunspot AR2371. You can keep an eye on it and the rest of the sun via SOHO's many real-time views of our star's tumultuous surface and neighborhood.