Here is the text for the revision challenge. You can find other information and photos showing solar flares by typing "solar flares" into your favorite Internet search engine.

Solar Flares

For those of us who work with satellites, solar flares are a particularly interesting problem. They are mostly unpredictable phenomena that we cannot foresee, and we are just now beginning to understand how they affect the delicate hardware that we send up into space.

Solar flares happen when a large amount of magnetic energy is discharged from the sun's atmosphere. When a solar flare occurs, observers on Earth and those using observation tools like the SOHO satellite witness a huge burst coming from the sun. In some cases, the sun also emits an incredible burst of x-rays, which are a form of light. Other particles like heavy nuclei, electrons, and protons are released too. This is called a coronal mass ejection. The picture included here shows one of the larger bursts that we have seen recently, which occurred on October 21, 2003. This flare disturbed many of the earth's communication systems and power systems when its emitted electromagnetic waves slammed into the earth's atmosphere and magnetosphere. Fortunately, it takes awhile for the solar storm to reach the earth, so we had time to put our satellites on standby.

The effects of a solar flare are significant. Here on earth, the effects are not immediately noticeable. Your radio or mobile phone may pick up some static. False alarms might be triggered on alarms, like your car. But up in space, the effects can be pretty serious. The emitted x-rays can charge up components on satellites, causing damage. Probably the best known effect of solar flares are the colorful auroras which are visible in the sky, especially in northern parts of the country.

Even though the effects are usually not immediately noticeable here on earth, they are still important. The high-energy particles that are released during a solar radiation storm can expose airplane passengers to radiation that is equivalent to ten chest x-rays. Also, navigational systems, especially ones close to earth or on earth can be bothered, creating orientation problems. Weather is effected by solar flares, too.

Another interesting thing about solar flares is that they tend to follow eleven year cycles. The last "solar maximum" was in 1989. During those periods there are many sunspots and coronal mass ejections. Satellites often need to be shut down to avoid damage. Even the SOHO satellite, which is used to observe the sun for the NOAA, cannot continue to operate during the largest of solar storms. It needs to be put on standby during the height of a solar storm.