Scientists Say: Solar wind

This is a gust of plasma that continually billows off the sun in all directions

The solar wind is responsible for both beautiful auroras that can light up the night sky and space-weather storms that can mess with power grids and cause blackouts.

Nick Fitzhardinge/Getty Images

Solar wind (noun, “SOL-er WIND”)

The words “solar wind” might make you picture a light breeze. But the solar wind is a torrent of energetic charged particles streaming out from the sun in all directions. This plasma contains mostly protons and electrons. There are also some atomic nuclei in the mix. These particles come from the sun’s corona. That’s the outermost layer of the sun’s atmosphere. The corona is so hot that gas particles can gain enough energy to escape the sun’s gravity. As these solar wind particles sweep out into space, they can drag magnetic fields from the sun with them.

The solar wind whips off the sun at two different speeds. Some of the wind flows out at about 800 kilometers (500 miles) per second. That material spews out of funnel-shaped openings in the sun’s magnetic field, called coronal holes, near the sun’s poles. Slower wind rolls off the sun at about 400 kilometers (250 miles) per second. Observations from the Parker Solar Probe hint that this flow comes from small coronal holes near the sun’s equator.

The solar wind washes over Earth at hundreds of kilometers per second. Most of this rush of plasma is deflected by Earth’s magnetic field. This creates a pattern in the solar wind flow like water rushing around a rock in a stream. But the solar wind plays an important role in space weather that affects Earth. Especially strong gusts of solar wind can wreak havoc on satellites, power grids and other technology. The solar wind isn’t just a nuisance, though. Solar wind particles light up Earth’s skies with auroras. They set auroras aglow on other planets, too.

In a sentence

Solar wind particles could seed the moon’s surface with ingredients for water.

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Maria Temming is the assistant editor at Science News for Students. She has bachelor's degrees in physics and English, and a master's in science writing.

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