There's a solar Coronal Mass Ejection travelling towards us at 1,400 miles per second, the largest solar storm since 2005. It will hit Earth around 2pm GMT, causing fluctuations on the power grid and disruptions to the Global Positioning System.
Don't worry, you won't die.
But there's something else, a strong proton storm — ranking S3 on a 5-level scale — which is in full rage now and gradually increasing. While CMEs are normal — about 2,000 every 11-year solar cycle — proton storms are very rare. Only a couple of dozen happen per solar cycle. And this one can be dangerous.
The storm has already affected aircraft traffic and may affect satellites' computers. On a telephone interview, NOAA's Space Weather Prediction Center physicist Doug Biesecker told me that, fortunately, there are measures to avoid most dangers.
"Many airliners have been avoiding the North Pole routes because they are more exposed to the proton storm, which disrupts High Frequency radio communications," he said on a telephone interview. HF datalinks are crucial to modern airflight, as they keep aircraft connected to Air Traffic Control. Due to the structure of the magnetic field that surrounds Earth, the polar cusps have very little protection against outbursts of solar radiation, so any airplane crossing that area could be exposed to this mayhem.
He also said that satellites may be affected, causing reboots on onboard computers as well as noise in imaging systems and interferences in telemetry caused by something called single event offsets. These events may change the values of the telemetry data. Since we are aware of these interferences in advance, engineers on ground bases can take them into account and make corrections before firing any commands that may jeopardise the life of the spacecraft.
The only real unpredictable danger is a total hardware failure, with a proton hitting an electronic component and killing it. But according to Biesecker, this "is a very remote possibility."
Global positioning systems are also affected — and will be even more affected tomorrow. Regular humans will not notice this. You will be able to keep using your GPS normally, but people using high precision GPS equipment — like oil drilling, military, engineering and mining operations — will definitely notice the problems.
NOAA's scale says that an S3 proton storm may pose danger to passengers in high-flying aircraft at high latitudes, which is why some airplanes below the 65th parallel north are now actually flying at lower altitudes to avoid any kind of radiation nastiness.
They also recommend for astronauts to stay home and avoid space walks but — according to Biesecker — this type of storm is "far below the level needed for the ISS to take any extraordinary protection measures." If it's ok for them, you can be sure it's perfectly fine for you and me down here on good old planet Earth.
When the Coronal Mass Ejection arrives to Earth at 1,400 miles per second, we will have a geomagnetic storm and a radio blackout. This, apart from the possibility of awesome auroras at latitudes as low as France, means several things.
First, the radio blackout will be level R2, which is moderate. According to the NOAA scale, it will cause "limited blackout of HF radio communication on the sunlit side and loss of radio contact for tens of minutes," as well as "degradation of low-frequency navigation signals for tens of minutes." Nothing that you should worry about.
The geomagnetic storm will only be "strong G2 with possibilities of G3," according to Bisecker. In the best case scenario, only power lines will be affected. You will not notice it because any power fluctuations will be handled by companies at the grid level. If the storm is long enough, however, it may damage power grid transformers.
Other than all this, and unless something extraordinary happens, you shouldn't worry about the world ending tomorrow. It won't. But keep your eyes open for auroras happening near you. Those living up north in particular will have a great show today and tomorrow.