Scientists classify the
severity of solar flares according to the amount of X-rays
they emit, known as X-ray flux. The GOES satellite measures
the X-rays coming from the sun at any given time—see
the graph of live data below.
Looking at this graph, you can easily identify
flares as sharp spikes—the higher the spike, the larger
the flare. A spike that reaches up into the zone marked 10-5
or higher is likely to have effects here on earth. Spikes that
don’t reach this high are generally inconsequential flares.
Use the horizontal scale (Universal Time)
to figure out when the flare happened. The data on this graph
are automatically updated every five minutes.