The Sun burst out a large coronal mass ejection (CME) June 20, formed from a recently-discovered giant hole in the sun's atmosphere that covers one-quarter of its diameter. Billions of tons of charged particles from this outburst are now racing toward the Earth.
Speeding along at over 4.8 million MPH, particles from this storm could begin to reach Earth as soon as June 22. These velocities were measured by the Solar Terrestrial Relations Observatory operated by NASA and the Solar and Heliospheric Observatory, operated jointly by NASA and the European Space Agency (ESA).
As the particles reach Earth, their travel will be deflected by the planet's magnetic field, warped around the planet. This can create conditions known as a geomagnetic storm, which could create bright northern and southern lights over the poles. These storms typically last about two days. As the particles from the solar ejection change direction, they will also temporarily alter the shape of the outer layer of our planet's magnetic field.
Storms like this have been known to cause power surges in power grids, so there is a small chance of some electrical interruptions in scattered areas. The particles streaming in could affect satellites, however. The MESSENGER, STEREO B and Spitzer telescope may be vulnerable to the effects of this geomagnetic storm. If mission planners deem it necessary, these spacecraft could be put into safe mode until the storm passes.
This coronal mass ejection occurred on the eve of the summer solstice. The Sun is currently headed toward a solar maximum, when activity on the Sun is at its greatest. Storms like this may increase in frequency before becoming less common as the Sun continues its 11-year cycle.
On June 18, NASA released a picture taken of a new, large hole in the corona (atmosphere) of the Sun. This hole is 400,000 miles across, or more than 50 Earths laid side-to-side. Solar wind, a stream of particles that constantly pours off the Sun in every direction, are prevalent in such coronal holes, and particles released from these features travel away from the star at speeds up to 1.8 million MPH, about twice their normal speed. Such coronal holes were first discovered by Skylab in the early 1970's.
There is no real danger to humans from this ejection, as the Earth is protected from direct exposure to the particles by our planet's magnetic field. But, look out for northern lights on the nights of June 22 and 23. You could be in for a treat.