By Evan Salveson | Updated Aug 30, 2022
Solar flares and solar winds both originate in the Sun’s atmosphere, yet they behave very differently. While satellites and space probes give us a direct view of solar flares, solar winds are invisible to the naked eye. Their effects, however, are visible when the aurora borealis and australis paint the night sky.
Solar winds are high‑energy streams of charged particles—primarily protons and electrons—that escape the Sun’s corona and travel through interplanetary space. The corona, the Sun’s outermost layer, reaches temperatures close to 2 million °F (≈1.1 million °C). Solar wind particles travel at roughly 559 miles per second (≈900 km/s), reaching the Earth’s magnetosphere and the atmospheres of all planets in our solar system.
On the solar surface, magnetic loops known as prominences can be enormous; a single prominence could hold about 15 Earth‑sized planets, according to Northwestern University’s Qualitative Research Group. A solar flare begins when two such loops collide, short‑circuiting each other and ejecting vast amounts of high‑energy plasma at light speed. NASA scientist Gordon D. Holman notes that a single flare can release energy 10 million times greater than a volcanic eruption. Stanford University’s Amara Graps compares a flare’s temperature to boiling water, explaining that 10 million Kelvin is about 30,000 times hotter than the boiling point of water.
Solar winds are a constant feature of the Sun’s ever‑expanding corona. Solar flares, however, follow the Sun’s 11‑year magnetic cycle. At the beginning of a cycle, the Sun’s magnetic field is weak, producing fewer flares. As the cycle progresses and the magnetic field strengthens, sunspots—visible indicators of flare activity—become more frequent.
The Earth’s magnetic field deflects most solar wind particles, but during powerful geomagnetic storms the wind can compress the magnetosphere, disrupting satellite communications and occasionally causing temporary loss of service for TV and cellular networks. Solar winds also shape comet tails by pushing away ice and dust from a comet’s nucleus, creating the characteristic tail that trails behind the comet.
Understanding these two phenomena helps scientists predict space‑weather events and protect Earth‑bound technology from their effects.
