Solar Wind and Storms
NARRATOR: From our home on Earth, roughly 93 million miles away, the Sun appears to glow gently, sending a steady stream of heat and light our way.
But how much, and exactly what kind of energy and matter the Sun releases changes all the time, depending on what’s going on beneath its surface.
This means the environment of our solar system is constantly changing, creating “space weather” around our planet.
Like weather on Earth, solar conditions are moderate most of the time. Even though the Sun belches out a million tons of energetic particles every second, this “solar wind” is so spread out, it’s like a warm, steady breeze.
But sometimes, space weather can take a sudden turn for the worse. Violent storms erupt, with the potential to cause serious damage.
There are two main kinds of storms: solar flares and coronal mass ejections, or CMEs for short.
Flares and CMEs are closely related, and start the same way: with fluctuations in the Sun’s magnetic fields. These magnetic lines themselves are invisible, but we can see them light up as they channel bright, hot flows of solar plasma.
The most common storms, solar flares, tend to be quick, powerful, and localized–like intense thunderstorms.
They shoot high-energy particles, as well as x-rays and gamma rays, away from the Sun at incredible speeds. A single flare can release the energy equivalent of 10 million volcanic eruptions or more than a billion hydrogen bombs.
CMEs are bigger, slower, and more spread out–more like a hurricane. These huge eruptions of plasma from the corona start out narrow, but they soon expand to about 30 million miles across. And traveling at speeds of up to 4 million miles per hour.
Like gathering clouds, sunspots offer a clue that storms might be brewing.
SARAH GIBSON (High Altitude Observatory): A sunspot is a massive region, several times the size of the Earth, which appears on the Sun as a dark spot. It’s dark because it’s relatively cool compared to its surroundings. And it’s cool because the magnetic fields are so strong that they’re suppressing the flow of heat from below.
NARRATOR: The Sun sends storms out in every direction, and Earth is small and far away, so we’re largely oblivious to all this solar activity.
But a small percentage of solar storms do hit Earth. And, when they do, they can cause serious damage.
ARCHIVAL MATERIAL CREDITS
“Secrets of the Sun”
National Geographic Television and WGBH Educational Foundation
Hinode is a Japanese mission developed and launched by ISAS/JAXA, with NAOJ as domestic partner and NASA and STFC (UK) as international partners. It is operated by these agencies in co-operation with ESA and NSC (Norway)
U.S. Department of Energy
SOHO (ESA & NASA)
Alistair Cameron / "Gentle Marimba"