giovedì 2 novembre 2017
SOLAR WIND TO GRAZE EARTH: A stream of solar wind flowing from a hole in the sun's atmosphere is expected to graze Earth's magnetic field on Nov. 2-3, passing mainly to the south of our planet. The glancing pressure of the gaseous stream could cause magnetic unrest around the poles. Arctic sky watchers should be alert for auroras mixed with bright moonlight. Free: Aurora Alerts.
SOLAR MINIMUM RETURNS: Today the sunspot number is zero as the sun resumes its transition to Solar Minimum. Images from NASA's Dynamics Observatory show no dark cores on the face of the sun:
This development continues a years-long trend of decreasing sunspot numbers -- with a notable interruption in September 2017, which brought a surprising outburst of large sunspots and intense solar flares. The disappearance of sunspots signals a weakening of the sun's magnetic field and a change in the character of space weather. During Solar Minimum, space weather is dominated by solar wind streams and cosmic rays, not sunspots and solar flares. Bonus: Solar Minimum auroras are gorgeous.