[Eaker]

Before SOHO, Earth had little or no warning before being hit by a shockwave of high-energy, radioactive particles from the Sun.

Either it can predict a flare before it leaves the Sun or we only get roughly 8 minutes warning.

[Fatuncle]

No. Light's travel time from Sol is 8 + minutes. Particles, having more mass, are ejected at less speed, and can take hours to make the trip.

It is quite possible to see a magnetic shock wave and flare ejecta by the light it emits well before it hits.

[spunkets]

"Either it can predict a flare before it leaves the Sun or we only get roughly 8 minutes warning."

Light takes 8min. The satellite is placed st 1/10th of the distance to the Sun, so the warning for any light is only 0.8min. Light doesn't matter though, it's the dust kicked up from the Sun that does. That takes ~24 hrs, or longer to get here. That moving dust cloud is what the warning is for. What the satellite can see is the dust cloud interacting with Sunlight and itself. Folks on Earth can't see that, because it's covered up by the atmosphere and the Earht's ionized layers.