The Sun is in a constant state of upheaval and occasionaly large erruptions, know as coronal mass ejections, occur which throw off huge clouds of gas into interplanetary space. A time
sequence of one such event is shown in the montage of CDS images above. Light emitted from helium atoms at a temperature of approximately 20,000 degrees was used to create the
images. the total mass ejected in this kind of event can be up to 1000 million tonnes. One of SOHO's priority tasks is to learn more about the onset and development of these events with
the aim of one day being able to predict them. Surprisingly, however , the new SOHO/CDS data have shown that there appears to be very little obvious activity low down in the
atmosphere prior to the ejection. It is as if these violent events begin with a whimper rather than a bang, an effect which may make forecasting them even harder than was previously
thought. The white disk plotted on the first image shows the Earth to the same scale.
Last revised on .