Seen from Earth, the northern lights are nothing short of dazzling. But it takes an astronaut’s eye view to really appreciate just how big and spectacular these light shows really are.
“Absolutely unreal,” NASA astronaut Josh Cassada tweeted (opens in a new tab) February 28 along with a lovely image of green aurora borealis swirling around the Earth’s northern latitudes. Cassada took the photo from the International Space Station, which orbits about 400 kilometers above Earth on average.
While the ethereal green glow will look familiar to anyone who has seen one aurora in pictures or in person, Cassada’s unique vantage point reveals just how incredibly far-reaching the phenomenon can be, stretching hundreds to thousands of miles around the planet’s poles.
Auroras, also known as Northern Lights seen in the Northern Hemisphere, occurs when charged particles emitted by the Sun slam into various molecules in the Earth’s atmosphere. The solar particles ionize these molecules, or remove electrons from them, causing the molecules to glow. Ionized oxygen molecules emit the fluorescent greenish light we most commonly see from the aurora borealis; nitrogen molecules emit red or pink light, while hydrogen and helium molecules release blue and purple light, according to Canadian Space Agency (opens in a new tab).
The phenomenon is most often seen at high latitudes, as charged solar particles tend to zoom along the Earth’s magnetic field lines, which end at the north and south poles. But when the sun belches an exceptionally large blob of plasma called a coronal mass ejection (CME) in our way, it can cause larger, more widespread auroras to appear at much lower latitudes than usual.
The sun has been particularly temperamental lately, with two CMEs slamming into our planet on February 26 and 27, according to sister site Live Science Space.com (opens in a new tab). This sudden influx of charged particles likely powered the enormous aurora that Cassada saw from space.
CMEs are becoming more common as the Sun approaches the peak of its 11-year cycle of activity, which is currently estimated to occur in 2025. Solar activity has increased significantly in recent months, with powerful solar flares shoot off from the star’s surface every few days. They are harmless to humans, for the most part. But exceptionally strong CMEs can damage satellites, trigger radio blackouts and even cause power outages on Earth. Scientists are constantly monitoring the Sun for signs of such ejections. Sometimes they see sun that smiles back.