December 21, 2006 NASA's twin Solar Terrestrial Relations Observatories (with appropriate acronym of STEREO) sent back their first images of the sun this week and with them a view into the sun's mounting activity. STEREO utilizes two nearly identical spacecraft on different trajectories to study the most energetic events on the surface and in the lower atmosphere of the Sun, and their travel through interplanetary space. Data from the spacecraft will allow scientists to construct the first ever three-dimensional views of the Sun, providing a new perspective on Coronal Mass Ejections (CMEs). CMEs are violent explosions on the surface of the Sun that can propel up to 10 billion tons of the Sun's atmosphere, at a million miles an hour, out through the corona and into space.
The two STEREO spacecraft were launched together on a Delta-II on Oct.25, 2006 from Cape Canaveral Air Force Station, Fla. Both spacecraft flew by the Moon taking advantage of a gravity assist that has propelled one of the observatories into an orbit "ahead" of the Earth in its journey around the Sun, and the other "behind" our planet as it makes its yearly revolution.