NASA’s Interstellar Boundary Explorer (IBEX) spacecraft has stared back “downwind” to look at the sun’s own tail. Much as the sun’s solar wind blows out the tails of comets, the vanishingly thin stuff between the stars blows the charged particles and magnetic fields of the solar wind back into a tail. The effect is much the same as when the sun’s “wind” of charged particles and magnetic fields blows a comet’s gas and dust into a tail. Most stars have such tails, as here imaged by telescopes. IBEX rendered the sun’s “heliotail” by recording uncharged atomic particles streaming toward it from the direction of the tail. Contrary to predictions, the sun’s tail is slightly twisted by the interstellar magnetic field and reflects the varying intensity of solar wind emissions back on the sun. As best as IBEX researchers can tell, the heliotail disperses some 1000 times farther from the sun than is Earth.
