Auroras occur when charged particles from the sun's solar wind interact with Earth's magnetic field (at altitudes above 50 miles, or 80 km). During intense solar storms, the Northern Lights become more spectacular and can sometimes be visible as far south as Texas.
The colors in an aurora are caused when oxygen and nitrogen particles mix with the charged particles in the atmosphere. The colors depend on what gas is involved and how high in the ionosphere the reaction takes place.
- Oxygen usually causes a green or brownish-red display.
- Nitrogen causes a blue or red color.
- Helium produces blue or purple colors.
- The height of the displays can occur up to 620 miles (1,000 km), although most are between 80-120 km.
Auroras have been a source of wonder for thousands of years. Images of auroras have even been seen in ancient cave paintings in France. The best chance to see the northern lights occur between the months of March through April and September through October, or anytime there is a solar storm.
The disturbances behind the aurora also have effects only realized in the modern world. Intense storm activity on the sun and the increase in charged particles interacting with Earth’s magnetic field can disrupt power grids, satellite communications and even radio communications.






