EARTH — A severe geomagnetic storm last week painted the night sky brilliant colors over Jackson Hole, along with many parts of the U.S. that aren’t typically treated to aurora borealis sightings. But what exactly do we know about the northern lights?
The National Oceanic and Atmospheric Administration’s (NOAA) Space Weather Prediction Center shared information about the phenomenon for curious stargazers. According to NOAA, the aurora borealis (the Latin term for the northern lights, named for the Roman goddess of the dawn) is the result of collisions between fast-moving electrons and oxygen and nitrogen gases in the Earth’s atmosphere.
“These electrons originate in the magnetosphere, the region of space controlled by Earth’s magnetic field,” NOAA’s website states. “As they rain into the atmosphere, the electrons impart energy to oxygen and nitrogen molecules, making them excited. When the molecules return to their normal state, they release photons, small bursts of energy in the form of light.”
During a geomagnetic storm, billions of this type of collision are occurring, generating enough photons to be visible to Earth-dwellers. Solar winds direct the particles along magnetic field lines toward the Earth’s north and south poles.
The different colors of the aurora are dictated by the gas involved in the energy exchanges. Oxygen emits greens, yellows and reds, while nitrogen emits blues. Ultraviolet light is also emitted by oxygen and nitrogen molecules.
While the aurora is known for lighting up the night sky, it can still occur during daylight hours, but the dimness of the photons can’t compete with sunlight, rendering it undetectable.
NOAA noted that scientists are still looking for answers regarding the different shapes visible in an aurora, but know that “the shape of the aurora depends on where in the magnetosphere the electrons came from and on what caused them to precipitate
into the atmosphere. Dramatically different auroral shapes can be seen in a single night.”
Visitors to the South Pole might get to see the aurora australis, a.k.a. the southern lights. Astronauts might get to see auroras on Jupiter and Saturn. According to NASA, any planet with an atmosphere and a magnetic field could see an aurora.
