The core of galaxy NGC4261 is 45 million lightyears away. Because light from very distant objects takes so long to reach us, we see these objects as they were in the distant past. The light from our nearest galaxy, Andromeda, takes 2.2 million years to reach Earth. The basic telescope design of the Hubble Space Telescope is called Cassegrain, after its 17th century inventor. Draw a simplified picture of each of the various types of optical telescopes.
Light travels faster than sound.
You can use this fact to estimate your distance from a thunderstorm. Count the number of seconds between the flash of lightning and the clap of thunder and divide by five to estimate the number of miles away the lightning struck.