- Aurorae are created when solar particles collide with Earth‘s atmosphere, exciting the earth’s magnetosphere which gives off light. The auroral lights are seen in the sky as different colors, depending on what gas molecules they excite.
- The sun constantly shoots out solar particles. These travel across space and sometimes hit Earth‘s magnetic field (called the magnetosphere). This collision makes gas molecules in Earth’s upper atmosphere (called ionosphere) give off light. This is what creates auroral lights that people see in the sky as different colored lights – or white during an extended “white-out” period.
- The light from the aurora is called the aurora. The famous Northern Lights are seen as a series of bright bands or curtains across the sky. You can see these bright curtains of lights at night from space because they glow bright enough to be seen from outer space.
- The poles of the Sun produce different colors of auroras, depending on their location on Earth. Northern Lights are typically greenish to red, while southern lights are usually blue. These colors come from ionized oxygen atoms in our atmosphere reacting with incoming solar particles.
- So how do we know that the aurora lights we see in the sky are the result of solar particles? We can measure them and see that they correspond with large solar proton events and proton weathers that take place on Earth. Higher energy particles from these storms reach Earth’s atmosphere, causing auroras to happen when they hit it. The energy from these storms allows us to measure both their strength and their location on Earth.
- Aurorae happen at the north and south pole because the Earth’s magnetic field lines bend there, allowing solar particles to bombard Earth’s atmosphere. The magnetic poles of the Sun are also at different locations than our geographic North and South Poles are. Coincidence? We think not.
- There are seven major types of aurora, which are categorized by their coloration or how they appear in the sky. They are also categorized by where they appear in the sky–low, high, or very high up in the atmosphere. Lower banded auroras are typically red or pink, while higher banded auroras tend to be green or blue in coloration.
- Lower banded auroras are similar to the aurora that happens on Earth. Because they are only 5-6 miles above the ground, they appear to be much brighter than other types of aurora. Green/blue auroras are blue because they happen when gas molecules in the ionosphere absorb the light from solar particles striking them. Red/pink auroras are red because high energy particles caused by solar storms knock electrons off of oxygen atoms in our atmosphere.
- The colors of the lower banded aurora correspond with changes in solar activity. If there is a big sunspot on the Sun, for example, then there will be more intense lower banded auroras over that area. Those that are more intense happen to be the most colorful.
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