LASCO C2 image of a CME
Active region 10486 on the Sun, which was already under close scrutiny by several instruments on board SOHO and other satellites, as well as numerous ground observatories, started up a spectacular two-part show in the morning on Tuesday 28 October 2003.
An X 17.2 flare, the second largest flare observed by SOHO, set off a strong high energy proton event and a fast-moving Coronal Mass Ejection (CME), hitting the Earth early on Wednesday 29 October. The encore came on Wednesday afternoon, when an X 10.0 flare from the same active region set off another round of particles and another fast-moving CME.
This image shows the CME cloud of the first flare emerging from the Sun on 28 October 2003. It is a composite view of two images, one by the C2 camera of the Large Angle and Spectrometric Coronagraph (LASCO) and one by the Extreme ultraviolet Imaging Telescope (EIT). The LASCO camera is equipped with an occulting disk that blocks out the Sun to be able to study the faint details in the corona. The EIT image of the Sun's disk has been superimposed on the occulting disk in the LASCO C2 image. The EIT image of the Sun's disk is to scale.