A solar mass Ejection (CME) propelled a solar storm against tuesday, which should reach Earth today, creating some coronal activity

Earth A CME propelled toward Earth on June 21 may be moving slower than originally thought. Analysts at the GSFC Space Weather Lab have downgraded the cloud's probable speed from 500 to 400 miles per second (800 to 650 km/s). Impact is now expected on June 24 at 07:00 UT and a weaker blow to Earth's magnetic field is expected.

Forecasters now predict a relatively mild G1-class geomagnetic storm when the cloud arrives

Late in the evening on June 20 the sun emitted a long lasting C7.7 small class flare that peaked around 04:28 UT. A C-class flare is a relatively small flare.

The flare was associated with a coronal mass ejection that bloomed off the sun at 04:12 UT. The movie shown above was captured by the Solar and Heliospheric Observatory spacecraft.

Preliminary NASA modeling shows the CME to be moving in Earth's direction at almost 800 km/s.

These 3D Heliospheric animated models, developed by the Community Coordinated Modeling Center based at the Goddard Space Flight Center, show how the CME cloud might appear as it sweeps past Earth. Credit: NASA/CCMC

Written by Karen C. Fox/Susan Hendrix, NASA's Goddard Space Flight Center