A giant hole has opened in the atmosphere of the Sun, and it's blasting out a high-speed wind that is directed right at Earth.
The incoming blast of solar particles is worth getting excited about: we're in for a moderate (G2) geomagnetic storm starting around Saturday June 14, according to the NOAA's Space Weather Prediction Center.
A coronal hole is a region where the magnetic fields on the surface of the Sun weaken and open up. This allows the wind of charged particles that constantly gusts from the Sun out into the Solar System to escape more freely.
When it rushes past Earth, some of the particles become entangled in Earth's magnetic field, sometimes with stunning results.
The particles are whisked away on magnetic field lines to high latitudes, where they are dumped out into Earth's upper atmosphere. There, they interact with particles in the atmosphere to produce a dancing glow – the light of the auroras borealis and australis.
A G2-level storm (the scale goes up to G5, which is only seen extremely rarely) is one that doesn't pose a significant danger. Some satellites may need to issue minor course corrections, and there may be some high-frequency radio blackouts.
The exciting part for us humans is the likelihood of aurora, from the poles down to a maximum latitude of around 55 degrees north and south. The Northern Hemisphere is getting very close to the summer solstice, which is the shortest night of the year, so viewing hours may be somewhat limited.
We've been absolutely spoiled for auroras this solar maximum, the most active period in the Sun's 11-year activity cycle – but that's no reason not to get out there and enjoy the fireworks.