NASA and JPL announced yesterday that Voyager 1 had, by their evidence, provably entered the interstellar medium and left the protection encapsulation of the sun's magnetic fields, a vast bubble called the heliosphere. But while it is in interstellar space, passing through the much higher density of much higher energy particles that exist outside the heliosphere, Voyager 1 is still within the solar system!

How is this possible? I explain at Boing Boing. This doesn't lessen the achievement nor the science that Voyager can still perform for several years to come. But it's a great moment to explain the shape and size of the solar system.