'Cannibal CME' could trigger auroras tomorrow: Where, when to watch?
What's the story
A powerful solar storm, known as a "cannibal CME," is headed toward Earth and could illuminate the skies with stunning northern lights over the Labor Day weekend. The phenomenon was triggered by a long-duration M2.7 flare from sunspot Active Region 4199 yesterday. The eruption sent a fast-moving coronal mass ejection (CME) toward our planet, which is expected to arrive late on September 1 into early September 2.
Storm forecast
CME expected to intensify into G3 storm
The National Oceanic and Atmospheric Administration's (NOAA) Space Weather Prediction Center has predicted that the CME will trigger G2 (moderate) geomagnetic storming upon its arrival. The conditions are expected to worsen into a G3 (strong) storm as the bulk of the solar event passes on September 2. This could result in auroras being visible further south than usual across parts of the northern US, including states like Oregon, Illinois, and New York.
Storm merger
Cannibal CMEs are solar storms that consume 1 another
Space weather physicist Tamitha Skov has revealed that there are actually two Earth-directed solar storms, with one possibly overtaking the other. This phenomenon is called a "cannibal CME." The UK Met Office has also confirmed this, predicting that the auroral oval will be "significantly enhanced" after the CME arrives. However, they warn that a waxing gibbous Moon could hinder visibility of these stunning displays.
CME impact
What are CMEs and how do they affect Earth?
CMEs are huge explosions of plasma and magnetic field from the Sun. They can create colorful auroras when they collide with Earth's magnetic field. However, these solar storms can also interfere with satellites, radio communications, and even power grids in more severe cases. The NOAA categorizes geomagnetic storms on a scale from G1 (minor) to G5 (extreme), with G3 being strong enough to bring auroras to mid-latitudes like those in the US.