FORM A 1. Two stars have the same size and have the same temperature, but one is twice as far away as the other. The planets appear to move in the sky through the constellations of the zodiac. The planets move in elliptical orbits with the Sun at the center of the ellipse.
Inferior planets take more time to go around the Sun than superior planets.
Light from an extremely hot star ionizes the hydrogen gas around it. The electrons recombine. Galileo Galilei 13. We all know that astronauts experience weightlessness in space. After sunset, we have about half an hour of twilight.