WIND - Here, There & Everywhere

Narrator (April Hobart, CXC): We've all felt the wind – whether as a gentle breeze or the wrath of an angry storm. But what exactly is wind and what impact does it have?

By definition, wind is the flow of gases on a large scale caused by differences in pressure. And even though most of us only think about it as it occurs on Earth, wind has been found on other planets in our Solar System, in the space in between planets, around stars, and even across galaxies. No matter where wind is found, it can have a big impact through its ability to move particles from one place to another.

Let's look at the Earth. Wind can blow here for just a moment or two, like in that gentle breeze or during a thunderstorm. It can also last for long periods of time, such as with the jet stream that is caused by the difference in the absorption of solar energy between climate zones across the planet.

If we look even farther out on the Sun, we see that the heating of the upper solar atmosphere produces what scientists call the solar wind. This wind is a stream of charged particles that flows away from the Sun at speeds of millions of miles per hour. When the solar wind hits the Earth's upper atmosphere, the impact of these charged particles can cause giant geomagnetic storms that can generate auroras (aka, the "northern lights") and knock out power grids.

And on even a larger scale, some unusual galaxies undergo bursts of star formation, often as a result of collisions between galaxies. The most massive stars that are created race through their evolution and explode as supernovas. If the rate of supernovas is high enough, the combined effects of the many supernova shock waves creates and drives a galactic-scale wind that blows across the galaxy. A prime example of this is the galaxy known as M82. Galactic winds such as the one in M82 are rare today, but they were much more common billions of years ago when collisions of galaxies were more frequent.

Wind is an excellent example of a phenomenon that happens here, there, and everywhere. By studying wind wherever it occurs – here on Earth, somewhere in the Solar System, or across the vastness of galaxies – we are learning more about how science is connected no matter where it is found.