A Wind From The Sun.

A wind from the Sun blows through our Solar System . The behaviour of comet tails as they flapped and waved in this interplanetary breeze gave astronomers the first hint of its existence. Streaming outward at 250-400 miles/second, electrons and ions boiling off the Sun's incredibly hot but tenuous corona account for the Solar Wind - now known to affect the Earth and other planets along with voyaging spacecraft . Rooted in the Solar Magnetic Field , the structure of the corona is visible extending a million miles above the Sun's surface in this composite image from the EIT and UVCS instruments onboard the SOHO spacecraft . The dark areas, known as coronal holes, represent the regions where the highest speed Solar Wind originates.