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Makes me miss Alaska

post #1 of 4
Thread Starter 
I'll never forget the night I heard the Northern Lights for the first time. Thousands and thousands of tinkling bells. We were way up in the interior of Alaska and it was phenomenal.

Northern Lights
post #2 of 4
Gosh those pics are absolutely gorgeous!!! I would LOVE to see something like that up close- its amazing. I have a question though- what exactly causes this phenomena? Why is there a sound that accompanies it? I'm so intrigued by this sort of thing, thanks for the link MA.
post #3 of 4
Thread Starter 
But I found this:

When you think of a big storm, you think of wind, rain, and snow. You think of staying inside with hot cocoa and warm blankets while tree branches lash about wildly outside. Big storms on Earth are exciting and scary. Weather on Earth changes the way the world looks, smells, and sounds.

Did you know that there are also big storms in space? There is a wind that blows past our planet coming from the Sun. Sometimes when there is a solar flare, Earth gets caught in a space storm with big gusts of "solar wind." Usually, we can not see, hear, or feel this space weather. That's because the Earth is well protected by the magnetic field that surrounds our planet. It's the same magnetic field that causes your compass needle to point north.

Sometimes a really big space storm causes something that people can see - strange lights in the sky called the Northern Lights. The Northern Lights are also called aurora borealis. This is what the famous scientist Galileo named them 400 years ago -- it means "northern dawn."

Northern Lights can be white, green, red, blue, or purple. They also have lots of different shapes. Some look like a star burst, some look like swirls, some look like giant curtains in the sky. The lights can shimmer, wave, or twist into eerie and mysterious patterns.

On April 4, 2000, there was a big explosion on the Sun. Some of the hot gas from the explosion headed toward Earth. When it hit Earth's magnetic field two days later, our planet was plunged into the biggest space storm since March 1989. Although the Northern Lights are usually seen only in far-north places like Canada and Alaska, the aurora during this storm were spotted in southern places like Texas and Florida. The sky turned beautiful shades of red, yellow and purple. It was a big storm!

When a big blast of solar wind hits the Earth's magnetic field, as it did on April 6, a lot of things happen. First, the magnetic field gets squeezed. Then it bounces back like a rubber ball. The vibrating magnetic field causes atomic particles to rain down on Earth's atmosphere from above. These raining electrons and protons collide with molecules of gas in our atmosphere. Each collision causes a tiny flash of light. When billions and billions of crashes cause enough light for us to see the in the dark sky, we call it the aurora borealis.

It took scientists a long time to figure out that tiny light flashes from crashing and colliding electrons and protons cause the Northern Lights. More than 2000 years ago the great philosopher Aristotle thought he knew the answer. He believed that the Earth and the heavens were two spheres, one inside the other. The Earth gave off gas and vapors during the day known as elemental fire. These vapors rose from the Earth and touched the sphere of the Heavens. Aristotle thought that the vapors would sometimes burst into flames, making lights in the sky.

Four hundred years ago Galileo had a different idea. He thought that Aristotle's vapors had risen above the dark shadow of the Earth's night and were reflecting the coming dawn. That is why he named them the "boreale aurora" - northern dawn.

In the 1700's, the famous astronomer Edmund Halley discovered that the Earth's magnetic field changes from year to year and from place to place. This was an important clue!

Around the same time, a Swedish scientist named Olaf Hiorter set up a magnetic needle, like a compass needle, that pointed in the direction of Earth's magnetic field. Whenever the Earth's magnetic field moved, the needle moved, too. He kept track of the Northern Lights and checked his magnetic needle for 6638 hours in a row! Whenever there were lots of aurora, the needle wiggled back and forth a lot. He decided that Northern Lights were definitely connected with changes in the magnetic field.

By 1800, the Earth's magnetic field was considered to be a major scientific mystery and many scientists tried to study it. Alexander von Humboldt loved science. With an assistant, he studied a magnetic needle under a microscope every half-hour for over a year! What he found was that there were many small changes and sometimes there were huge changes. He called the big changes magnetic storms. He then got other scientists to carefully observe magnetic needles in different places and found that magnetic storms happened at the same times in all the different places.

In 1852, Edward Sabine looked at sunspot records and realized that the pattern of sunspots was the same as the pattern of Northern Lights. When there were lots of sunspots, there were lots of Northern lights. What did this mean? In 1859, Richard Carrington saw a huge solar flare and noted that 18 hours later there was a huge magnetic storm on Earth! What was the connection? Many other scientists and mathematicians worked at the clues.

In the 20th century, when NASA spaceships were able to take pictures of Earth's magnetic field from outer space, scientists began to understand. The Sun and the Earth are connected! When there is a solar flare, a powerful wind blows from the Sun toward the Earth. The solar wind crashes into our magnetic field, pushing and squashing it. The magnetic fields and electric energy smash, bend and mix. This is a space storm.

Atomic particles that hit oxygen molecules in the upper atmosphere cause red-colored auroras. Oxygen at lower altitudes flashes green. Nitrogen glows with blue and red lights. Some people who watch the colorful auroras say that there is a crackling, hissing sound. Scientists aren't sure what causes these sounds.

Watching aurora is fun and exciting. Normally you can only see them in far north places like Alaska and Canada. Sometimes, during a big space storm, they light up the skies as far south as Florida and Mexico! Since the solar maximum (the peak in an 11 year cycle of sunspot activity) is almost here, there will be lots more space storms. You can read the news from NASA at http://science.nasa.gov and watch for alerts about stormy space weather. They will tell you when would be the best time to watch. The further north you live, the better your chances of seeing the aurora. Most auroras are seen around midnight. They usually do not last for long, but they are extraordinarily beautiful. If you have a chance to see them, don't miss it!
post #4 of 4
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