Spacecraft
STEREO-A
One of a pair launched together and set drifting to either side of the Earth, so that the Sun could be seen from two places at once and coronal mass ejections could be measured in three dimensions rather than guessed at from a disc. Its twin fell silent in 2014; this one is still going, and passed back between the Sun and the Earth in 2023.
- Agency
- NASA
- Launched
- 2006-10-26 - still working
Path
A loop round the Sun slightly smaller than the Earth's, so it runs slightly faster and slowly laps us: years ahead of the Earth, then round the far side, then back.
Along the way
- Swung past the Moon and out into orbit round the Sun
- With its twin, the first view of the whole Sun at once
- Passed back between the Sun and the Earth, 17 years on
Everything the map shows is worked out in your browser from published orbital data - nothing on it is a stored picture of where things were.