Skip to main content

Aurora seen over Morgantown

Solar weather provided a rare view of the northern lights last weekend in Morgantown. Prof. Christopher Fowler shared some insights into the science behind the aurora:
Our Sun emits a continuous stream of charged particles outward into our solar system, known as the solar wind. When these particles encounter the Earth, they are usually deflected around the planet by the Earth's protective magnetic field (our magnetic field is why a compass points north). However, when conditions are just right in the solar wind, a process called “magnetic reconnection” provides some of the solar wind particles access to our atmosphere. These solar wind particles stream into the northern and southern hemispheres and collide with atoms in our atmosphere. When this happens, the atoms will glow, and this glow is the aurora. The color of the glow depends on the atom or molecule that is glowing: at Earth, green and red aurora are most common, and are caused by oxygen atoms glowing at altitudes of 100-200 km (green) and 200-300 km (red). On rarer occasions, blue aurora can be observed, caused by nitrogen glowing beneath altitudes of 100 km. The color of the aurora is determined by the energy of the solar wind particles entering the atmosphere: more energetic solar wind particles can reach deeper down into the atmosphere. 
You might ask why we don’t see aurora in Morgantown more often: the final part of this puzzle is because of the Sun. Every so often the Sun will belch: when it does so, it can suddenly eject huge numbers of solar wind particles to space at high speed and in a very short time. If this “Sun vomit” happens to encounter Earth as it whizzes through the solar system, and conditions are “just right," it can enter our atmosphere and cause the aurora. The many extra particles in this Sun-belch make the aurora brighter than usual, and if the belch is big enough, these particles can reach much farther south than usual. Our Sun follows an eleven year cycle known as the “Solar cycle." We are currently at “solar max," which is when the Sun is mostly likely to belch more often and more impressively. The most impressive auroral displays occur when conditions are “just right” as the Sun lets out an impressively large belch. This combination doesn’t happen too often, which is why we don’t see aurora in Morgantown all of the time.

Did you miss the aurora over Morgantown last weekend? Check it out through the eyes of the WVU Department of Physics and Astronomy! More photos are available on our social media pages

Five pictures showing the aurora as seen over Morgantown, WV