Solar Events

Active Region: A region of enhanced activity on the sun's surface that is associated with a complex magnetic field. An active region may be spotless (plage) or have one or more spots. Active regions are designated by a number when they appear on the visible part of the sun (the visible disk). They are also categorized by their complexity with a rating ranging from alpha (simple) to gamma-delta (multiple complexes). The more complex a region, the more activity (M- and X-flares, etc.) that region produces.

Coronal Mass Ejections (CME): Ejection of a large mass of plasma, including electrons, which are mostly caused by large solar flares. CME's directed towards the earth usually impact the planet between 36 and 96 hours after the ejection. CME's are responsible for increased A- and K-indices by increasing the solar wind velocities. These solar wind velocities may vary from 200km/h (small flares) to 900km/h (large flares).

Coronal Stream: A stream of charged particles originating from the sun's corona. Coronal streams have similar effects as CME's by increasing the A- and K-indices but usually to a lesser extent. However, a few coronal holes may cause major storm levels at the higher latitudes on earth resulting in total propagation fade-out at these latitudes.

Filament: A slow moving "cord-like" mass of plasma which moves across the sun's surface. Since most filaments are darker in color than the surrounding surface they are often visible in optical telescopes.

Prominence: A slow moving large mass of plasma on the sun's surface. Prominences are larger than filaments and are constantly changing in shape.

Proton Flares: An eruption of protons (positively charged nuclear particles) from the sun's surface. Protons usually reach the earth within an hour after the flare and they usually impact the earth at the polar regions where the magnetic field lines converge attracting these charged particles. Protons cause the ionosphere to absorb radiowaves at the polar regions.

Solar Flares: Solar flares are large eruptions of energy and charged particles from the sun's surface. They are usually accompanied by coronal mass ejections and/or proton flares. Solar flares may last from minutes to hours.

Solar Wind: The constant stream of charged particles originating from the sun. The solar wind has speeds ranging from 200km/s to 700km/s, but under certain circumstances such as fast moving CME's or coronal streams, the solar wind speed may increase to around 900km/s.

Sunspot: A small spot on the sun's visible surface where the magnetic flux lines converge. Sunspots appear darker than the surrounding surface area because they are relatively cooler in temperature.