3. The invisible buffer zone with space - atmospheres, magnetospheres and the solar wind

The Sun's two winds

The space just outside the Earth is not empty. It is filled with pieces of the Sun. Our star is expanding out in all directions, filling interplanetary space with electrically-charged particles that are forever blowing from the Sun. This solar wind moves past the planets and engulfs them, carrying the Sun's rarefied atmosphere out to the space between the stars. So, we are actually living in the outer part of the Sun.

Unlike any wind on Earth, the solar wind is a tenuous mixture of charged particles and magnetic fields streaming radially outward in all directions from the Sun at supersonic speeds of hundreds of thousands of meters per second. It is mainly composed of electrons and protons, set free from the Sun's abundant hydrogen atoms, but it also contains lesser amounts of heavier ions. The seemingly eternal wind carries a magnetic field with it, with one end anchored in the Sun. This interplanetary magnetic field has a spiral shape due to the combined effects of the radial solar wind flow and the Sun's rotation.

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Copyright 2010, Professor Kenneth R. Lang, Tufts University