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Geomagnetic storm on its way, June 22 and 23

It’s due to arrive sometime today (June 22, 2015). NOAA forecasters estimate a 90% chance of polar geomagnetic storms when the CME arrives. Aurora alert!

June 21, 2015 full-halo coronal mass ejection, or CME, from the sun. It's an expanding cloud of electrified gas from the sun. Read more about CMEs. CMEs aimed at Earth are sometimes called halo events by scientists because of the way they look in these images, which are made by NASA's Solar and Heliospheric Observatory (SOHO

June 21, 2015 full-halo coronal mass ejection, or CME, from the sun. It’s an expanding cloud of electrified gas from the sun. Read more about CMEs. CMEs aimed at Earth are sometimes called halo events by scientists because of the way they look in these images, which are made by NASA’s Solar and Heliospheric Observatory (SOHO)

UPDATE: Geomagnetic storm strikes! Awesome auroras … See photos

A coronal mass ejection (CME) left the sun early Sunday morning and is joining forces with two earlier CMEs that left the sun a few days ago. All are now heading directly for Earth, with a strong potential to spark auroral displays. It doesn’t mean we’re due for a major space weather event. That depends on how how the magnetic field of the CME connects to Earth’s magnetic field when the CMEs arrive. However, space weather forecasters at NOAA are estimating a 90% chance of polar geomagnetic storms when they do arrive sometime today (June 22, 2015). NOAA forecasters wrote that Sunday’s CME, a much faster CME than the earlier ones, is …

… expected to catch up with the two observed on June 18 and 19, bringing them all to Earth in close succession by the UTC day of June 22, 2015.

The CME was associated with an R1-Minor flare event observed at 0142 UTC (9:21 p.m. ET) from Sunspot Region 12371 located near center disk.

A G3-Strong Geomagnetic Storm Watch has been issued for June 22, as well as a G2-Moderate Watch for June 23 as the CMEs make their way past Earth.

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Sunspots June 20, 2015 from EarthSky Facebook friend Alexander Kozik.  Afocal photography through Plossl 32mm and Celestron XLT 102 refractor.

Sunspots June 20, 2015 from EarthSky Facebook friend Alexander Kozik. Afocal photography through Plossl 32mm and Celestron XLT 102 refractor. Never look at or photograph the sun without a special filter.

This is the earlier solar flare - on June 19, 2015 - from Sunspot 2371.  The June 21 flare released a faster CME, which will catch up to it and join forces with it before encountering Earth on June 22.

June 19 flare from Sunspot Region 12371. The June 21 flare released a faster CME from this region. The CMEs will join forces before encountering Earth on June 22.

View larger. | Details on the June 21 CME, from NOAA.

View larger. | Details of the June 21 CME, from NOAA.

Bottom line: A fast-moving CME is joining forces with two earlier CMEs. All three are due to arrive sometime today (June 22, 2015). NOAA forecasters estimate a 90% chance of polar geomagnetic storms when the CME arrives. Aurora alert!

Deborah Byrd

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