corona

NASA's Parker Solar Probe is the first spacecraft to fly inside the Sun's corona — here's what it has found and why it matters.

The solar wind is a continuous outflow of charged particles, mostly protons and electrons, from the Sun's hot corona. It moves at roughly 400 to 800 km/s, bends the interplanetary magnetic field into a spiral, inflates the heliosphere, pushes comet ion tails away from the Sun, drives auroras, and helps strip planetary atmospheres. Voyager 1 crossed the heliopause, where the wind gives way to interstellar space, in 2012.