24 June 2015

Earth experienced a geomagnetic storm on June 22, 2015 due to the arrival of an Earth-directed coronal mass ejection, or CME, from June 20.
The CME originated at 10:24 p.m. EDT on June 20, 2015. Coronal material exploded from the sun at about 780 miles per second, arriving at Earth at 1:59 p.m. EDT on June 22.
NOAA rated the resulting geomagnetic storm as G4, or severe. To see how this event affected Earth, visit NOAA's Space Weather Prediction Center at http://spaceweather.gov, the U.S. government's official source for space weather forecasts, alerts, watches and warnings.
A geomagnetic storm happens when the plasma and magnetic fields in a CME interact with Earth's magnetic field, disturbing the magnetosphere and allowing stored plasma to flow towards the magnetic poles.
The same active region produced two other CMEs in the past few days, which were pushed along by the faster Earth-directed CME from June 20.
As a result of the geomagnetic storm, aurora were sighted in several mid-latitude locations, including Virginia in the United States and in the United Kingdom.

Image:
(Top-Left) Two views of the CME on June 20, 2015 from the Solar and Heliospheric Observatory, or SOHO. Earth-directed CMEs like this one are often called halo CMEs, because the material shooting off from the sun looks like a ring around the disk of the sun. This halo can be seen more clearly in the right-hand image called a difference image, which is created by subtracting two consecutive frames to see how the image has changed.
(Top-Right) Aurora as seen 30 miles west of Philadelphia, PA on June 23, 2015.
(Bottom-Left) "My first Aurora! Three brilliant, visible-to-naked-eye, displays of pink-hued Aurora with the last ending around 1:30 a.m. What an unforgettable sight at 38 degrees latitude!" said Michael Charnick of Calhoun County Park, WV.
(Bottom-Right) "The most intense aurora I've ever seen. It started with a wall of light between Lake Preston and DeSmet, South Dakota, while the moon was still out."