🌌 Aurora

Scientific Overview & Physics

The aurora is the visible signature of space weather. Charged particles from the Sun, funneled by Earth's magnetic field, slam into oxygen and nitrogen atoms in the upper atmosphere and make them glow — green from oxygen at 100–300 km, red at higher altitudes, blue and purple from nitrogen.

How It Works

The aurora begins with the solar wind, a continuous stream of charged particles flowing outward from the Sun. Most of that wind is deflected around Earth by its magnetic field, but some particles get captured and funneled along magnetic field lines down toward the north and south magnetic poles, where the field lines converge and dip into the atmosphere. As these energetic particles collide with oxygen and nitrogen atoms roughly 100 to 300 kilometers up, they transfer energy to those atoms' electrons, briefly exciting them to a higher energy state. When each electron falls back down to its normal state, it releases that extra energy as a photon of light — a process called excitation, essentially the same physical mechanism that makes a neon sign glow. Different gases and altitudes produce different colors: oxygen at typical auroral altitudes glows green, the most common auroral color; oxygen at higher, thinner altitudes glows red; and nitrogen produces blue and purple hues, often visible along the lower edges of an active display. During a strong geomagnetic storm, when the Sun has launched a large coronal mass ejection toward Earth, far more particles get funneled into the atmosphere across a much wider area, expanding the auroral oval away from the poles and making the aurora visible from far lower latitudes than usual.

What You Can See or Experience

A strong aurora display is easily visible to the naked eye as shifting curtains, arcs, or rays of light, often green with hints of red or purple along the edges, moving and pulsing across the sky over the course of minutes. Cameras, even ordinary smartphone cameras with a night mode, are typically far more sensitive to faint aurora than the human eye, often capturing vivid color in a long-exposure shot when the display looks like only a faint gray-green glow in person. Dark skies away from city lights dramatically improve visibility, and because the aurora forms in a ring-shaped zone around each magnetic pole, checking a location's latitude against the current forecasted extent of that ring is essential for knowing whether a display will actually be visible overhead.

Connection to Earth and Everyday Life

The same charged particles that produce the aurora can, during a strong storm, induce unwanted electrical currents in long-distance infrastructure like power grids and pipelines, disrupt high-frequency radio communication, and degrade GPS accuracy — making the aurora simultaneously one of the most visually spectacular and most closely monitored space weather phenomena.