Realizing a solar flare travels at the speed of light,
The EM part yes, but the particle shower that is the real hazard, by definition, cannot travel at the speed of light. Why do you insist on ignoring this basic rule of physics?
There are many kinds of eruptions on the sun. Solar flares and coronal mass ejections both involve gigantic explosions of energy, but are otherwise quite different. The two phenomena do sometimes occur at the same time – indeed the strongest flares are almost always correlated with coronal mass ejections – but they emit different things, they look and travel differently, and they have different effects near planets.
Both eruptions are created when the motion of the sun’s interior contorts its own magnetic fields. Like the sudden release of a twisted rubber band, the magnetic fields explosively realign, driving vast amounts of energy into space. This phenomenon can create a sudden flash of light -- a solar flare.
Flares can last minutes to hours and they contain tremendous amounts of energy. Traveling at the speed of light, it takes eight minutes for the light from a solar flare to reach Earth. Some of the energy released in the flare also accelerates very high energy particles that can reach Earth in tens of minutes.
The magnetic contortions can also create a different kind of explosion that hurls solar matter into space. These are the coronal mass ejections, also known as CMEs. One can think of the explosions using the physics of a cannon. The flare is like the muzzle flash, which can be seen anywhere in the vicinity. The CME is like the cannonball, propelled forward in a single, preferential direction, this mass ejected from the barrel only affecting a targeted area. This is the CME—an immense cloud of magnetized particles hurled into space. Traveling over a million miles per hour, the hot material called plasma takes up to three days to reach Earth. The differences between the two types of explosions can be seen through solar telescopes, with flares appearing as a bright light and CMEs appearing as enormous fans of gas swelling into space.