450 kilometers/sec near the Earth, but there are low-speed and high-speed streams within this wind that travel 200 to 2000 km/sec. The wind blows with essentially the same speed all the way out to the orbit of Neptune, and it is expected that by a distance of 150 Astronomical units it impacts the interstellar medium and forms a shock front where it suddenly decelerates. This is called the heliopause, and the Voyager and Pioneer spacecraft are expected to reach it in the early part of the next century.