Aurora borealis green sky

The aurora borealis, a green luminous phenomenon in the night sky, is caused by solar particles colliding with Earth's atmosphere.

About this subject

The aurora borealis, also known as the northern lights, is a natural light display that occurs in polar regions. The phenomenon happens when charged particles from the solar wind are channeled by Earth's magnetic field and collide with oxygen and nitrogen molecules in the atmosphere, exciting them and emitting light. The green color, the most common, results from interaction with oxygen at altitudes between 100 and 300 km. Although often associated with winter, the aurora can be observed year-round in places like Norway, Sweden, Finland, Canada, and Alaska, provided there is dark, clear sky. The 11-year solar cycle influences intensity: during solar maximum, auroras are more frequent and brighter. Historically, peoples like the Vikings and the Sami interpreted the lights as gods or spirits. Today, the aurora borealis attracts tourists and photographers, being one of the most photographed phenomena in the world. Aurora photography requires equipment with high ISO sensitivity and long exposures, as well as geomagnetic activity forecasts.

Frequently Asked Questions

What is the best time to see the aurora borealis?

The best time is between September and March, during the northern hemisphere winter, when nights are long and dark. Locations near the Arctic Circle offer higher probability.

Can the aurora borealis be seen in Brazil?

No, the aurora borealis occurs only at high latitudes. In Brazil, the equivalent phenomenon is the aurora australis, which is rarely visible at low latitudes but can be observed in Antarctica and the extreme south of South America.

What causes the green color of the aurora?

The green color is produced by the excitation of oxygen molecules at altitudes between 100 and 300 km. Other colors, such as red and purple, occur at different altitudes or with other gases.