| Propagacja |
| This is a "coronal hole"--a region where the sun's magnetic field opens up and allows solar wind to escape. NASA's STEREO-A spacecraft has sampled the solar wind stream and measured its velocity: ~575 km/s (1.3 million mph). NOAA forecasters say there is a 45% chance of G1-class geomagnetic storms when the stream arrives on Jan. 20th. |