Xin An

Ahead of the bow shock that Earth creates in the solar wind, giant bubbles of rarefied gas sometimes appear. Inside them, particle density drops by factors, and electric fields start to tremble like a plucked string.

The Moon isn't just hanging in the sky: it leaves behind a long tail of disturbed solar wind. The stream of charged particles from the Sun flows around the rocky sphere, and behind it forms a zone where particles are almost absent. But this emptiness is not simple: electric fields arise in it that push apart the remaining electrons and ions.