Celestial Tour: Probing the Mysterious Aurora

Produced by the Space Telescope Science Institute’s Office of Public Outreach in collaboration with NASA’s Universe of Learning partners: Caltech/IPAC, Center for Astrophysics | Harvard & Smithsonian, NASA Jet Propulsion Laboratory, and Sonoma State University 

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 Text, Probing the mysterious aurora. On some nights, colorful dancing lights put on a mesmerizing performance in the sky. An image of the night sky over trees illuminated with waves of red, yellow, green and blue colors filling the sky. 

Text, the show starts slowly, perhaps with an arc of light hovering above the horizon. A photo of the edge of a lake with a ribbon of green light at the far end in the sky. Text, the glow steadily brightens and stretches to cover more of the sky. Suddenly, the arc begins to bend and twist. An image of the green light growing and areas of red and purple appearing with rays rising into the sky above. Text, Suddenly the arc begins to bend and twist and the sky bursts into a kaleidoscope of color. These dancing lights are the aurora. A video of greenish lights streaming, swirling, and dancing across the sky. Text, But what changes the aurora's tempo from a steady waltz to a wild salsa? 

The Earth seen from space. A magnet appears over it. Text, Earth is like a giant bar magnet with north and south magnetic poles and invisible field lines surrounding the planet. This magnetic field is what causes compass needles to point toward the poles. A compass face with arrows pointing north, south, east, and west and a spinning hand. 

A blue-colored video of bright rays streaming and bursting from the Sun. Text, Earth's magnetic field protects us from swarms of high speed charged particles that erupt from the Sun in sudden violent outbursts. 

An animation of the particles flying from the Sun through space towards Earth. Text, The magnetic field also shields us from a steady stream of charged particles expelled by the Sun called solar wind. 

An animation of the particles striking the lines of a magnetic field around earth. Text, the solar wind compresses the Sun-facing side of Earth's magnetic field and drags the opposite side into a long tail called the magnetotail. Some solar particles are carried away by the magnetotail while others speed along magnetic field lines toward the poles. Particles that reach the poles slam into atoms and molecules in the upper atmosphere causing them to glow. This glow is the aurora. 

Red and green aurora in a starry sky over the silhouette of trees and a hill. Text, The aurora's color depends on what kind of atom or molecule is hit and how high up the collision happens. Green, the most common color, is given off by oxygen atoms about 60 miles up. But higher in the atmosphere, oxygen atoms produce a vivid red glow. 

An image of streaks of bright purple in the sky. Text, Nitrogen is usually responsible for rare blues and purples. An image of ribbons of greenish yellow with pink at the edge. Text, As well as low lying fringes of purple or pink. 

An image of blue-green light striping the sky above a forest in a curving line. Text, The shape of the aurora follows the shape of the magnetic field lines. Auroras often display vertical streaks or resemble curtains because the charged particles follow parallel field lines straight down. 

Streaks of purple blue in the night sky. Text, An aurora's appearance also depends on the observer's perspective. An aurora that looks like a wavy curtain of light to someone looking at it from the front might look like colorful smoke rising from the horizon to someone looking at it from the side or like a swirling tunnel of light to someone directly below it. Images of curtain-like green lights waving through the sky from 3 angles. 

An image of the dark Earth seen from space with a ring of green-striped light on its upper hemisphere. Text, from space, auroras look like ovals around Earth's poles, tracing where the magnetic field lines intersect earth. A NASA satellite imaged the ultraviolet glow of this auroral oval around Earth's north pole. An illustration of a ring around the north pole of Earth. Text, once in a while something happens in Earth's magnetotail that allows a wave of energetic particles to cascade toward the poles. this temporary rush of particles energizes the aurora, replacing its calm serenity with a wild and colorful commotion. The satellite image animates, showing flares of dancing light ringing the pole. Text, special thanks aurora photographers Dominic Cantin, Tom Eklund, Stan Richard. Space Sciences Laboratory, University of California Berkeley, Dr. Nahide Craig, Dr. Laura Peticolas. NASA Goddard Space Flight Center, Rani Gran, Walt Feimer.