The Sun is stormy and has its own kind of weather. It is so hot and active that even the Sun's gravity cannot hold its atmosphere in check! Energy flows away from the Sun toward Earth in a stream of electrified particles that move at speeds around a million miles per hour. Now that is fast! These particles are called plasma, and the stream of plasma coming from the Sun is called the solar wind. The more active the Sun, the stronger the solar wind.

The solar wind constantly streams toward Earth, but don't worry because a protective magnetic field surrounds our planet. The same magnetic field that makes your compass point north also steers the particles from the Sun to the north and south poles. The charged particles become trapped in magnetic belts around the Earth. When a large blast of solar wind crashes into the Earth's magnetic field, the magnetic field first gets squeezed and then the magnetic field lines break and reconnect.

The breaking and reconnecting of the magnetic field lines can cause atomic particles called electrons trapped in the belts to fall into the Earth's atmosphere at the poles. As the electrons fall to Earth, they collide with gas molecules in the atmosphere, creating flashes of light in the sky. Each atmospheric gas glows a different color. Oxygen and nitrogen glows red and green and nitrogen glows violet-purple. As these various colors glow and dance in the night sky, they create the Northern Lights (aurora borealis) and the Southern Lights (aurora australis).

The Northern Lights remained a mystery for thousands of years until NASA spacecraft were able to take pictures of Earth's magnetic field from outer space. Finally, scientists were able to study these pictures and understand how the Earth and Sun are connected. Today we even have space weather reports that alert us to strong solar winds approaching Earth.

Watching aurorae is fun and exciting, but normally you can only see them in places far north like Alaska and Canada. The movement of the aurora across the sky is usually slow enough to easily follow with your eyes but they can also pulsate, flicker, or even move like waves. During solar maximum, auroras are seen as far south as Florida and even Mexico! The aurora is usually just a red glow in the sky when you see it in the far south regions of the world. Astronauts have the best view as they can see them even better from space!

Aurorae often seem to be very close to the ground, but the lowest aurora is still about 100 km or 62 miles above the ground, a distance much higher than clouds are formed or airplanes can fly. A typical aurora band can be thousands of kilometers long, a few hundred kilometers high, but only a few hundred meters thick.

We hope you are able to see the Northern Lights at least once during your lifetime. We know you will never forget it!