Solar Flare by STEREO
On 25 March 2008, three big sunspots materialized on the Sun and one of them, sunspot 989, unleashed an M2-class solar flare, an intense, rapid release of energy from a localised region on the Sun. It was also associated with a coronal mass ejection (CME), which are huge bubbles of materials that erupt from the Sun’s corona.
This flare was captured by STEREO, a twin spacecrafts designed specially to observe the Sun. Movie: MPEG (10MB), Quicktime (2MB, 30MB). The movie shows about 14 hours of activity.
Three active regions were lined up across the centre of the Sun. The one on the far left produced the flare and CME. A careful look at the middle region reveals a burst of activity just before the flare blasts from the area to its left. This image is taken in extreme ultraviolet “light”, the light that our eyes cannot see, that’s why the Sun is not the familiar yellowish reddish colour. Credit: NASA/STEREO
STEREO (Solar TErrestrial RElations Observatory), launched in 25 October 2006, is a 2-year mission employing two nearly identical space-based observatories to provide the first-ever, 3-D “stereo” images of the Sun. One observatory will be placed ahead of Earth in its orbit around the Sun and the other behind. Just as the slight offset between your eyes provides you with depth perception, this placement will allow the STEREO observatories to obtain 3-D images and particle measurements of the Sun.
My Dark Sky 