The idea of a continuous stream of particles flowing outward from the Sun was first suggested by British astronomer Richard Carrington in 1859. A century later, physicist Eugene Parker said that comet tails always point away from the Sun simply because a “solar wind,” as he called it, pushes on them. Parker was widely ridiculed, and yet in the very next year the Soviet Luna I spacecraft detected such particles whizzing a million miles an hour. Nowadays the solar wind is routinely monitored by a fleet of spacecraft.
It has been assumed for decades that this wind eventually meets its match far beyond Pluto, where it encounters incoming atomic particles from the stars. The place where the two collide is called the heliopause. Signs of its existence have been detected by the Voyager spacecraft now speeding away far beyond Pluto. Astronomers think Voyager 1 will fully encounter this true edge to the solar system in 2015 when it is 133 Astronomical Units (Earth/Sun distances) away.
It is this still-mysterious heliopause that the NASA’s Interstellar Boundary Explorer (or IBEX) spacecraft was designed to study. But no one was prepared for the huge ribbon of fast-moving material that it detected in 2009, when it created the first all-sky map of energetic neutral atoms beyond the solar system’s fringe. This area, the spacecraft astoundingly reported, is dominated by a strange, enormous arclike feature soon dubbed the Ribbon.
The Ribbon is not just sitting there; it’s coming toward us. Many space physicists believe that the Ribbon is the result of the solar wind encountering the galaxy’s magnetic field, which then forces the charged particles to change direction, essentially reflecting them back. Along the way, the protons pick up stray electrons to create neutral high-speed atoms that continue inward. In other words, the Ribbon is an echo – an echo of our Sun.
A newer hypothesis ignores the Sun completely, and claims that as we orbit around the center of the Milky Way, our solar system is now traversing a cloud of energetic hydrogen gas about ten light-years across. This in turn is imbedded within a much-larger nebula of intensely hot gas called the Local Bubble. To see this so clearly and so closely would mean that the Sun and Earth are about to penetrate the thicker of the masses – probably within the next century. If true, our world is now poised to enter a million-degree cloud of interstellar gas, the probable remnant of one or more supernova explosions that went off just a few million years ago.
If so, the IBEX Ribbon is an alignment of gaseous boundaries, and we’re positioned just right to be sighting along its edge. If you blow a bubble, you barely see its center but easily observe its round outline; so, similarly, we’re now within a mere 93 billion miles of the boundary as we prepare to penetrate the thin hot gas, possibly in the lifetimes of our children.
It won’t be Armageddon. The Earth and Sun have already gone in and out of such hot nebulae in the past. Once we’re inside, the heliosphere may get pushed inward and shrink a bit. Cosmic radiation levels may rise slightly. Mutation and cancer rates may climb a bit. Future colonists on Mars or the Moon may need even more radiation protection than is now envisioned.
If this view is correct, the IBEX Ribbon is our first “red alert” of things to come.