NASA, 24 Aug 2014
A look at the coronal mass ejection (or CME) from August 24, 2014’s M5.9-class solar flare.
This image was taken with the LASCO C2 instrument on NASA/ESA’s SOHO spacecraft. This instrument is a coronagraph.
A coronagraph is a special type of telescope that uses a solid disk (“occulter” or “occulting disk”) to actually cover up the Sun itself, completely blocking direct sunlight, and allowing us to see the atmosphere around the outside of the Sun (known as the “corona”).
Looking at the black dot, that is the occulter disk. The Sun is completely blocked, allowing us to see that hot plasma of charged particles being ejected towards the side.
This image was taken at 14:18 UT so almost 2 hours after the actual solar flare. At the time of the flare the responsible active region AR2151 had just come over the eastern limb of the Sun and the ejected plasma was propelled towards to the side and not directly at Earth.
Credit: NASA Solar Dynamics Observatory (Little SDO)