Thirty years after launch but earlier than expected, Voyager 2 has left the cozy realm of our solar system, where the stream of particles from the sun dominates space.

You might think that space billions of miles from the sun is a placid, empty domain. In fact, Voyager 2 has been heading outward in the same direction as the solar wind, charged particles streaming from the sun, but things started to get a lot more complicated on August 30, when the spacecraft was 7.8 billion miles from the sun

There, the spacecraft passed into a new region, where the solar wind suddenly slams into the prevailing breeze and magnetic field left from a series of massive supernovas from 20 million to 30 million years ago

In this area, called the termination shock, the speed of the solar wind drops abruptly from about 250 miles per second to about 60

"There's something outside pushing in on the field of the heliosphere