Story includes realvideo of a coronal mass ejection. .
We have found a strong correlation between an S-shaped pattern on the Sun, called a sigmoid, and the likelihood that an ejection will occur from that region within days. As soon as we can recognize an S-shaped region, we know that it is more likely to erupt. Other common structures look like a butterfly, quite symmetric, and these rarely erupt. Coronal mass ejections are violent discharges of electrically charged gas from the Sun's corona, or outer atmosphere. The largest explosions in the solar system, they hurl up to 10 billion tons of gas into space at speeds of one to two million miles an hour.