What causes the auroras borealis?

Answer 1

Auroras are caused by radiation from the sun, called solar wind, interacting with Earth's magnetic field. When magnetic storms occur on the Sun, electrically charged particles (ions) from the corona and solar flares are added to the solar wind produced by the corona. Solar charged particles from the sun, which are normally radiated into space, sometimes get caught in the Earths magnetic field as they come into the upper atmosphere they react with other gases and produce coloured lights.

The Earth's magnetic field funnels particles from the solar wind over the polar regions (due to the magnetic nature of the Earth). The charged particles are accelerated by the Earth's magnetic field and interact with the gases in the upper atmosphere and cause the gas molecules to emit light. Electrons in the molecules are excited to higher energy levels by the accelerated charged particles and the electrons release photons when they fall back to lower energy levels.

When the ions from the sun first collide with air particles more than 80 kilometres above the ground, each causes a different reaction, and each reaction causes a different color to explode. Collisions of these particles with atmospheric molecules causes energy emission as visible light. Neutral nitrogen particles will create a purplish pink color, while ionic nitrogen transforms into a brilliant blue. If an ion crashes into oxygen in a lower altitude, it becomes the most common aurora, a yellowish-green color. If it however, collides with oxygen at a high level, it will create the rarest blood red aurora. An aurora is sometimes accompanied by a crackling sound. Auroras can occur on other planets.

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