Here Comes the Sun: Solar mass ejections -- a big one, or maybe two, happened on February 17th, and the leading edge hit Earth late on the 19th. More will be coming!

But don't worry. Even though up to ten billion tons of stuff, moving at 2000 kilometers per hour, might head our way in each event like this, it's spread pretty thin by the time it gets here, and there appears to be only secondary danger to people on the Earth's surface. More such events are expected as "solar max" reaches its peak in the next several months.

In fact, during solar max years like 2000, there are frequent mass ejections, which seem to be triggered by collapsing local magnetic field anomalies on the surface of the sun. If the ejection occurs near the center of the sun as seen from earth, (that is, if the collapsing field is pointing at us) observers see a "halo event", so called because the rapidly expanding mass of ejecta seems to form an expanding halo around the sun. Light and other electromagnetic energy associated with a halo event travels at the speed of light and can be seen on earth within a few minutes, but the leading edge of the cloud of slower moving particles (the "mass" that is ejected) takes a day or two or more getting here, depending on the violence of the ejections. For details go to And if you want to stay informed of what might be heading our way, subscribe to NASA's (free) Space Science Headline News at