It was learned last year that the space probe launched in 1977 had finally reached outside our solar system and into interstellar space. This was discussed in our cosmos minute Sunday morning. But how do scientists know this occurred?
It has to do with the Heliosphere. Think of it as the suns atmosphere, with a bubble of vast space surrounding the sun filled areas with planets, moons, and plenty of particles that can’t be seen by the naked eye. Plasma that is launched out from the sun, known as the solar wind, is what creates this bubble against the outside pressure and particles (like hydrogen and helium elements) that are flying through the interstellar regions, or the regions between stars. These solar winds flow outward at an extremely fast speed until they encounter the termination shock, where motion slows abruptly, like a traffic jam on an interstate. If our solar system were encased in a bubble, this is where the actual bubble structure would begin. If you continue through the edges of the bubble, you pass through the heliosheath which is that transitional region between the solar system and interstellar space, (it would be kind of like Earth’s ozone layer) and then pass through the heliopause. This is the edge of our solar system and the “physical” barrier between it and interstellar space.