Visiting in the Canyon I The canyon walls rise up into the black sky as if to frame the streak of light plunging down into the valley. It is awesome to think of the speed of this apparently motionless body as fine material is wisped away from its head. Comets are frozen, but the winds from the sun toward which it travels are hot enough to evaporate its material. When we look out at the comet from where we are, we see all of this evaporating material as it extends many hundreds of thousands of miles into space. The sun is very powerful. There are storms on the sun's surface. These storms contribute to the force of what we now know to be a "solar wind." This wind is made up of small particles called photons traveling at near the speed of light. It is this wind that helps form the tail pointing way up out of the canyon. Back