South Plains Astronomy Club

Observing Under The Dark West Texas Skies

Prominences are the “flames” that stick out from the edge of the Sun, like this one:

August 23, 2023 was an unusually calm day that also featured a beautiful huge prominence arcing from the Sun's edge.  For reference, the sunspot at lower right is roughly the size of Earth!
A large prominence arcing off the Sun’s surface on August 23, 2023. For reference, the sunspot at lower right is a bit bigger than the Earth! (109 Earths would fit along the Sun’s equator!) Photo by Tom Heisey

Prominences are magnetic fields that extend out from the Sun’s surface, bringing the surface material, made of Hydrogen plasma. Filaments are actually prominences viewed from overhead. The white areas on the Sun’s surface are active regions that are hotter than the surrounding material. The dark spots are sunspots, which are much cooler than the surface average. Prominences and filaments can reach heights many times the size of Earth and span 1 million miles across the face of the Sun.

These fields can form and break down in a matter of minutes or hours, but may remain almost unchanged for days. Think of the twisting rubber band under a balsa wood airplane. When the rubber band is relaxed (the magnetic fields run straight from pole-to-pole like Earth), the Sun is quiet. The Sun’s equator rotates faster than the poles, so the magnetic lines start twisting – The rubber band is twisted, but smooth. Eventually, the magnetic fields start bunching up, like the rubber band getting knotted up as the line twists more. Those knots become the prominences, filaments, and other features we see on the Sun.


Yesterday, we had a great example of such a quick change from a large prominence:

Animation of solar activity on Oct 26, 2023, including the collapse of a large prominence.
Images by Big Bear Observatory, CA and the National Solar Observatory https://gong2.nso.edu/
Animation assembled by Tom Heisey

If you are interested in the Sun, I encourage you to visit the NSO site, SpaceWeather.com, and the Marshall Space Flight Center Solar Physics site.