NASA satellites have discovered what powers the aurora borealis, or northern lights. The aurora borealis is a natural light display that occurs in the sky, primarily in the high-latitude regions of both hemispheres. It is caused by the collision of charged particles from the sun with atoms in the Earth's atmosphere.

The NASA satellites, called the Van Allen Probes, were launched in 2012 to study the Earth's radiation belts. The radiation belts are two regions of intense radiation that surround the Earth. They are formed when charged particles from the sun are trapped by the Earth's magnetic field.

The Van Allen Probes discovered that the aurora borealis is powered by a process called magnetic reconnection. Magnetic reconnection occurs when two magnetic fields come together and reconnect, releasing energy in the form of charged particles.

In the case of the aurora borealis, the two magnetic fields that come together are the Earth's magnetic field and the magnetic field of the solar wind. The solar wind is a stream of charged particles that is constantly emitted by the sun.

When the solar wind collides with the Earth's magnetic field, it is deflected away from the Earth. However, some of the charged particles from the solar wind can become trapped in the Earth's magnetic field. These charged particles then spiral along the magnetic field lines towards the Earth's poles.

As the charged particles approach the Earth's poles, they collide with atoms in the atmosphere. This collision causes the atoms to become excited and emit light. The light that is emitted by the atoms is what we see as the aurora borealis.

The Van Allen Probes have provided scientists with a new understanding of how the aurora borealis is powered. This new understanding will help scientists to better predict when the aurora borealis will occur and to understand how it affects the Earth's climate.