How strong is solar wind (compared to wind on Earth)?
Unlike wind on Earth, solar wind is composed of highly charged particles ejected from the sun. Although the solar wind can be used to move spacecrafts with “solar sails,” the two different types of wind are very different. The solar wind is deflected by the earth’s magnetic field, but it changes that field, compressing it on the sunward side and extending it away from the sun. Solar sails are still a theoretical concept–there aren’t any in use today. They would sail not on the solar wind but on the photon (light) pressure from the sun.
The solar wind is very weak compared to the wind on Earth, though it is much, much faster. When we measure solar wind speeds, we typically get speeds of 1-2 million miles per hour. They end up being weaker because there is very little of it. The solar wind density is usually about 100 particles per cubic inch. Thus, a typical pressure from the solar wind is measure in something called nanopascals whereas at the Earth’s surface, the atmospheric pressure is 100 kilopascals, and surface winds are about 100 pascals. Since solar wind is measured in nanopascals (10^-9 pascals) it is approximately 1000 million times weaker than winds here on Earth.
