How Solar Sails Work... Photon Pressure

Cosmos-1 can articulate its solar-sail blades. For example, when Cosmos-1's blades are all configured flat, and oriented face-on to the Sun, then sunlight exerts the most pressure on the whole spacecraft.

When Cosmos-1 has twisted all its blades so they're edge-on to the Sun, then it receives its minimum push from sunlight.

How Solar Sails Don't Work

Have you ever seen the radiometer from Edmund Scientific? It's a glass bulb containing some blades, painted black and white, that can rotate on a needle bearing. The air has been evacuated from the bulb so the blades can rotate freely without a lot of air resistance. While it does illustrate a form of motion caused by radiation, it works on a different principle than photon pressure (Cosmos-1 uses photon pressure). In the radiometer, light warms up the black sides of the blades. These then radiate their warmth as infra-red light, and the reaction from that radiation moves the blade.

Also, don't confuse photon pressure with the solar wind. The Sun constantly throws particles outward through the solar system. These particles, mostly protons and electrons, are called the solar wind. But these particles mostly pass right through Cosmos-1's sails. Cosmos-1 does not rely on the solar wind.