You would never know it just by looking in the sky, but almost every day, the Sun throws off billions of tons of super-hot gas in gigantic clouds. These clouds travel at millions of miles an hour, and if Earth happens to be in the wrong place at the wrong time - Kerpowie!

The Sun gives off a very strong wind from its outer layers, and this wind flows past Mercury, Venus and the rest of the planets in the solar system. In fact, you can even say that Earth goes around the Sun while still being INSIDE the atmosphere of the Sun! But don't worry. Even if you were in space you wouldn't notice anything going on at all. This wind is billions of times thinner than any wind we feel on the ground. The space between the planets is not empty at all. It is a rather soupy gas that can also carry many different kinds of storm clouds with it, and these storm clouds come from the Sun itself. The surface of the Sun is very complicated and full of very hot gases that are sometimes shot away from the Sun. Astronomers call one type of these events 'Solar Flares' and another kind 'Coronal Mass Ejections'.

Solar flares are pretty spectacular! Within an hour or less, an area of the Sun the size of Earth suddenly lets loose a blast of X-rays and other powerful radiations. Traveling at the speed of light, which can go 7 times around Earth in only one second, it still takes 8 1/2 minutes for these X-rays to get to Earth from the Sun. The BIG PROBLEM is that, because nothing can travel faster than light, we don't know that these X-rays are on the way until after they already get here, and then it's too late to run for shelter. During some of the most powerful solar flares, an astronaut in a space suit could actually get killed if he or she happened to be doing a space walk at the time. NASA, and astronomers, have been studying solar flares for over 50 years to learn more about what causes them, and to make it easier to forecast when the next one will happen so that astronauts won't be injured by them accidentally. Fortunately, the atmosphere of Earth is so thick that we never have to worry about even the most powerful solar flare here on the ground. The only thing that solar flares do is to knockout short wave radio communication during the daytime. These blasts of X-rays damage a part of the atmosphere called the ionosphere, and this lets radio signals from the ground get reflected like light is reflected from a mirror. A solar flare 'tarnishes' the ionosphere so that these radio signals don't bounce anymore. This used to be a big problem before the Space Age, but now we have satellites and other technology that doesn't rely on short-wave radio anymore.

The second type of storm from the Sun is the Coronal Mass Ejection, also called the CME. For reasons that astronomers don't fully understand yet, the sun occasionally 'burps' and send out huge clouds of gas into space. By the time they reach the orbit of Earth, they grow to be millions of miles across. Most of the time, these clouds are sent out in other directions than where Earth is in its orbit, but every few weeks they come charging right at us. They travel at about a million miles an hour and take 2-3 days to get here. Now it just so happens that Earth has a pretty stiff magnetic field, and a very thick atmosphere, so we never have to worry about these solar storm clouds as the sweep by Earth on their way to Pluto and beyond. The Earth's magnetic field, which looks kind of like a bar magnet, pushes most of the particles in these clouds away from us so they never really hit the planet at all. But even so, the CME material can make lots of trouble in other ways too.

As solar material streams past Earth, it stretches Earth's magnetic field like taffy being pulled. This makes Earth's magnetic field look like a comet with Earth at the head of it. The tail of Earth's field trembles and shakes, and sometimes it can even snap. When that happens, space weather becomes more than just some invisible storm between the planets. In a region of the tail nearly halfway to the Moon, there are particles trapped in the magnetic field. When the field snaps, these particles pick up energy from the magnetic field, and they begin to move at very high speeds. Within a few minutes, they travel towards Earth along the magnetic field. They get funneled into the polar regions where they collide with atoms of oxygen and nitrogen. These collisions give off light and we se this from the ground as the famous aurora borealis and aurora australis - the northern and southern lights.

People have worried about aurora for centuries, but they really are harmless. They can't get any closer to the ground than 70 miles or so, but optical illusions can fool the eye into thinking they get much lower and even touch the ground! Many people have claimed they hear sound from aurora, like the crackling of static electricity. Although sound waves cannot travel 70 miles through Earth's dilute atmosphere, scientists think that the crackling noise is real. It comes from electricity that is created in the ground by the powerful currents high up in the atmosphere. These ground currents, like miniature lightning bolts, cause sparks in pine needles and other sharp objects near the person that hears the noise.

If aurora were the only things that space weather causes, we wouldn't have much to really worry about, but unfortunately it is not that simple. We rely on communications satellites, military satellites, and a reliable electrical service to power our computers, televisions, air conditioners and to run our industries. Space weather can knock out satellites and even cause blackouts! In March 1989, the Canadian province of Quebec experienced a blackout that affected millions of people for a half a day. People were stuck in dark elevators; heating systems would not work to heat homes during the Canadian winter, and if it hadn't been for a bit of old fashioned good luck, many states from Maine to Georgia would have had electrical problems too! What happened was that a huge solar storm caused currents to flow in the ground under Canada. These currents of electricity found their way into the Quebec electrical power system. In 90 seconds, the engineers went from normal operation to full blackout! It isn't just blackouts that can happen. The most common way that space weather affects us is by damaging or disrupting communications satellites.

When was the last time you or your parents used a cell phone or a pager? When did you stop at a gas station and use your credit card at the pump to buy gas? Have you used the internet to visit web sites in Europe or elsewhere? Chances are pretty good that you or your family have relied on one or more satellites every day to handle your communications or other needs. These satellites are very expensive and they orbit Earth far enough out in space that they aren't as well shielded from space weather storms as you and I are here on the ground. Since 1996, 14 satellites have been affected by space weather events and nearly $2 billion has been lost in satellite technology from some kind of space weather event. In May 1998, nearly 40 million pagers went silent in North America because a satellite probably got clobbered by radiation from a space weather storm. Astronauts live and work in space on the Space Station, and even when they are inside, they get very high doses of radiation. In a few weeks they can get 30 times more radiation exposure than what we get here on the ground in a whole year! Many adults worry about going to the doctor to get a chest X-ray. Astronauts get more radiation in one week than what your parent would get from 100 chest X-rays! You don't have to be an astronaut to get zapped, either. If you plan to be an airline pilot or a stewardess, you will fly at altitudes of 40,000 feet for perhaps 900 hours every year. During a large solar flare, a passenger on a long flight could pick up as much radiation as in a chest X-ray. The flight crew, during a 900-hour tour of duty, would get exposed to much more than that, and in fact more radiation than what we allow for nuclear power plant operators!

So, space weather has many parts to it, and you don't have to be an astronaut to worry about storms from the sun!