Astro Bob

This is typically what you see at the start of a minor geomagnetic storm from the northern U.S. when the Kp = 5 — a low, quiet arc in the northern sky that's only visible from the countryside. To the eye it's often colorless, but the camera picks up the green glow of excited oxygen atoms in the atmosphere.  Bob King The latest forecast from the NOAA space weather folks predicts a Kp index of "5" from 6 to 9 p.m. Central Time Friday night, March 5 . If you live in the northern U.S. and southern Canada, that number indicates a minor geomagnetic storm. Kp is a measure of how vigorously the Earth's magnetic field is stirred up by high-speed particles arriving from the sun and ranges from 0 to 9. The higher the number the more vivid and extensive the aurora. On March 2, the Kp index was also 5, and although the aurora remained low and "quiet" during the early evening hours, it broke out into moving rays and bright arcs in the bottom of the northern sky later