Sparked by a medium-sized (C-class) flare, a long, magnetic filament burst out from the Sun, producing one of the best shows that SDO has seen (Aug. 31, 2012). Viewed in the 304 Angstrom wavelength of extreme ultraviolet light, the filament strand gets stretched outwards until it finally breaks and heads off to the left. Some of the particles from this eruption did hit Earth with a glancing blow on Sept. 3, generating some beautiful aurora. The video clip covers four hours of activity.
A very large and bright prominence erupted off the surface of the Sun around 19:00 UT on August 31, 2012 and just kept going. This video from the STEREO Behind spacecraft shows the prominence and the coronal mass ejection (CME) in which it is embedded as it leaves the Sun (orange, EUVI) and travels through the fields of view of COR1 (green), COR2 (red), and HI1 (blue) telescopes before it finally disappears from HI1 around the end of September 2, still clearly visible more than two days after it erupted. While CMEs are routinely seen in the Heliographic Imager (HI) telescopes, it's very rare for prominences to stay visible for so long. The HI1 field of view ranges from 4 to 24 degrees away from the Sun. To get a sense of scale, we know the Sun is roughly 860,000 miles wide?and look how far the prominence holds together. And this CME is so bright it initially saturates the COR1 telescope.
Also visible in the movie is the planet Venus, which appears as a bright spot on the right side of the COR2 field. Venus is extremely bright and its image is saturated on the COR2 detector. It also creates a couple of artifacts in the movie due to internal reflections within the HI1 telescope. The first of these artifacts is a loop-like feature near the position of the planet on the left side of the HI1 field. The second is a large bubble-like feature on the opposite side of the HI1 image--this is more easily seen at the start of the movie. Both of these artifacts are explained on the STEREO website.