For the first time ever, the satellites of the International Solar-Terrestrial Physics (ISTP) “Observatory” have tracked a solar eruption all the way from the Sun to the Earth. The resulting coronal mass ejection (CME) traveled 4 days through interplanetary space before arriving at Earth, where it caused violent disturbances of the magnetic environment and spectacular auroral displays. The initial expulsion occurred on the Sun on January 6, 1997, and the resulting magnetic cloud hit the Earth on January 10.
The Sun often erupts. It flings out whitehot ionized gas (actually hotter than whitehot, to where it glows in X rays) with explosive violence. Only occasionally is this gas aimed at Earth, however, and it is even more unusual for scientists to be watching the potentially disruptive mass ejection (as they were in January) just as it leaves the Sun. This made it possible to alert other scientific teams of possible activity they might observe 2 to 3 days later. It normally takes that long for such ejecta to travel the 150-million-km void from Sun to Earth. Thus while this is not the first, or the largest, event to be detected, the ISTP Observatory comprises a complement of spacecraft and ground-based missions that allows study of this “space storm” on a scale never accomplished before.