The large active region AR1944 erupted with a dramatic flare January 7th, and the corresponding coronal mass ejection is predicted to generate widespread auroras when it reaches Earth at about 8:00 UT on the 9th.

Update: Although moderate solar-radiation surges have been reported in Earth's vicinity (level S3), geomagnetic storms and auroral displays have not developed as expected. However, NOAA's Space Weather Prediction Center believes activity should continue through the day on January 9th and might result in moderate (G3) geomagnetic disturbances after sunset across North America.
Solar eruption on January 8th

A huge coronal mass ejection erupted from the Sun on January 7th Universal Time. Because it is headed toward Earth, the shock wave appears to bloom around the entire Sun in this animation of frames from the SOHO spacecraft. (The Sun, represented by a white circle, is masked out by the coronagraph.) The "snow" is a blast of high-energy protons from the event; these arrive in Earth's vicinity much faster.

NASA / SOHO Consortium /
Space-weather experts have been keeping an eye on active region AR1944 on the Sun's disk ever since it rounded into view on New Year's Day. This enormous feature, more than 120,000 miles (200,000 km) across, contains dozens of individual sunspots.

Yesterday AR1944 was the site of a powerful X-class flare at about 18:32 Universal Time. Spacecraft recorded the huge coronal mass ejection (CME) that resulted, and that blast is now heading our way. Forecasters at NOAA's Space Weather Prediction Center anticipate a strong geomagnetic storm when the shock wave reaches Earth tomorrow (Thursday) morning at about 8:00 Universal Time.

Solar-wind prediction for Jan. 9, 2014

The predicted view, as seen from far above the Sun, of the arrival at Earth (green dot) of a powerful solar-wind shock wave at 8:00 Universal Time on January 9, 2014. The panel at left shows the plasma's density and the one at right its velocity. Click here to see a time-lapse animation of these displays.


This arrival time corresponds to 3 a.m. on the East Coast and midnight on the West Coast. With the first-quarter Moon confined to the evening sky, the viewing prospects are excellent for a major auroral display (It's about time — things have been abnormally quiet during the past year's solar maximum.)

There's no guarantee that brilliant auroras will push down from their polar home to mid-latitudes. But skywatchers might want to set their clocks for some predawn viewing tomorrow morning.

Check this posting later today for updates.


You must be logged in to post a comment.