Curtains of Light in the North

Written by Studio AM.

An aurora can appear as a pale arc, a moving curtain, or rays across a dark sky. The light forms high in Earth's atmosphere when energetic charged particles transfer energy to atmospheric atoms and molecules. The energy ultimately comes from interactions between the solar wind and the region controlled by Earth's magnetic field.

Earth's magnetic field shapes their route. Many particles are guided toward high latitudes, so auroras are frequent around broad zones near the magnetic poles. Solar activity can disturb the space around Earth and expand the visible area.

Color depends on which atmospheric gas emits light, the energy involved, and altitude. Oxygen commonly contributes green and red light, while nitrogen can contribute blue or purplish shades. One color chart cannot capture every mixture or viewing condition.

The curtain shape also has a physical story. Particles follow magnetic field lines into the atmosphere, creating narrow rays and sheets of light. Perspective affects how those structures appear. Apparent movement reflects changing particle flows rather than fabric waving in air. An aurora therefore links events across enormous scales: activity near the Sun, magnetic guidance around Earth, and collisions among particles in the upper atmosphere. The visible display depends on all three.

Questions

Choose an answer. The explanation appears after you answer.

  1. Question 1 of 4

    What is the main idea of the passage?

  2. Question 2 of 4

    Why are auroras especially common near high latitudes?

  3. Question 3 of 4

    What does “emits” mean in the color paragraph?

  4. Question 4 of 4

    Which gas commonly contributes green and red auroral light?

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