Intense solar storms sometimes cause shimmering, often colorful lights called auroras to appear in the night skies. Usually they are visible from longitudes far north, but in the spring of 2001 intense solar storms can cause the lights to appear as far south as Mexico.

Some people, unaccustomed to seeing auroras so far south, actually reported the lights as UFOs.

The solar storms fueling these auroras were the result of the biggest sunspot cluster seen in a decade, which developed on the upper right quarter of the side of the sun visible from Earth according to satellite readings. A sunspot is a cooler, darker region on the sun’s surface caused by a concentration of temporarily distorted magnetic fields. It spawns tremendous eruptions, or flares, into the sun’s atmosphere, hurling clouds of electrified gas toward Earth at speeds in excess of a million miles (1.6 million kilometers) per hour. You can see a gallery of auroral photos from the storm at Spaceweather.com.

In this Web Lesson you will learn about solar winds and spectacular auroras.

Science Explained

What exactly is an aurora? An excellent place to find out is Alaska Science Explained by Neal Brown. Yes, as a matter of fact he is a rocket scientist. When the site opens, click The Aurora Explained where you will discover the Aurora Borealis — the Northern Lights.

There are four links on the page; start with Aurora Facts. An aurora, you will learn, is like a glowing neon sign. When the charged particles from the sun hit the ionosphere (earth's upper atmosphere), the atoms are energized and start to glow. Click Continue at the bottom of the facts page to find more facts.

Think >

• Why are auroras like a television set?
• What is the most common aurora color and why?
• Auroras are beautiful, but solar winds can be harmful. How so?

Paintings in the Sky

Learn more about auroras and see some great pictures at Auroras: Paintings in the Sky. When the page opens, read the introduction and click Self-Guided Tour. Here you will see a list of questions. Click the question you're most interested in, or go through them in order. Near the bottom of each page you will find movie or audio clips to check out as well.

When you're done exploring, go back and answer each of the questions you clicked on.

Summarize >

• What do auroras look like?
• What do they look like from space?
• What makes them occur?
• Where do you have to be to see them?
• Why are they different colors?

Space Weather

In most newspapers you can check out the weather report and weather forecast. If you want to check the space weather forecast, visit the Space Environment Center's Space Weather Now site.

You may not be used to looking at a space weather report, so let's look at a few things together.

• Auroral Map. This map shows you the current auroral activity at each pole as measured by satellites. Auroral activity is measured on a scale of 1 - 10 based on the amount of power deposited in a polar region. What is the current activity level?
• Solar Wind. This set of meters shows the speed, strength, and charge of solar winds — gasses being spewed from the sun and hurled toward earth.
• Active Region. This series of photos shows the current day's sun spot (solar flare) activity. Big spots mean big solar storms and big auroras. Click the image, or click here to find the today's date.

Northern Lights and Folklore

If you have time for one final stop, visit the Northern Lights Planetarium in Norway, where you will find a short article about the northern lights and folklore.

Think >

• What did auroras mean in Middle-Age Europe?
• What did the color red signify?
• If you wave at the northern lights, will they become more active?