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The Solar Wind - Sunlight on Steroids

A solar flare erupts on the surface of the sun.

In 1979, a massive jolt of solar energy particles smashed into the Skylab space station, throwing the unprepared station into the Earth’s atmosphere and raining debris over the Indian Ocean and parts of western Australia. In 1989, a much larger high-energy jolt of solar power penetrated the Earth’s atmosphere itself, knocking out the electric-power grid and causing blackouts across the northeastern United States and Canada.

The culprit: a gust of solar wind thrashing through outer space near the height of the sun’s 11-year-long “solar cycle.”

Solar wind is the holy grail of those competing in the great renewable energy chase. The ability to capture its volcanic-grade energy it has spawned serious discussions of space-based solar energy. The U.S. government has tasked the National Security Space Office.

The Solar Cycle

The sun generates energy according to a 11-year solar-cycle during which the energy exuded gradually increases from a low — solar minimum — to a high — solar max. The so-called “sunspots” phenomena is a key part of this cycle. Sunspots are small places on the skin of the sun where darkness and abnormally low temperatures prevail.

A “Small” Sunspot

The average surface temperature of the sun is 6000° Celsius while sunspots are about 4500° Celsius, which can last anywhere from a few hours to a few months. Sunspots expand and contract as they move across the surface of the sun and can be as large as 80, 000 km in diameter.

A cluster of sunspots on the surface of the sun.

Sunspots are surrounded by magnetic fields that insulate them from the heat. The field is strongest in the darker parts of the sunspots—called the umbra. The field is weaker and more horizontal in the lighter part—the penumbra. Ultimately, sunspots have a magnetic field that is about 1000 times stronger than the surrounding photosphere. During the solar cycle, the tension created by these magnetic fields triggers volcanic eruptions on the sun. These eruptions, in turn, unleash high-energy particles in colossal explosions called solar flares, which last anywhere from a few minutes to a few hours and release more than a billion tons of dynamite.

Solar flares occur near sunspots, usually near the line that divides oppositely directed magnetic fields. The largest flares usually occur during the years preceding and following the “solar max”. Solar flares release waves of energy that crash through the solar system until they exhaust themselves. These waves are called solar wind.

Solar winds routinely disrupt radio transmissions on Earth. As the energy from the solar flares hurdles through space, some of the high-energy particles penetrate a layer of Earth’s atmosphere called the ionosphere, which reflects radio waves to the surface of the Earth as they ascend into the ether. When the ionosphere is disrupted by the solar wind, static radio reception or a total loss of the signal usually follows.

Source: Images courtesy of NASA