EARTH seems big to man, but it’s a small planet orbiting a medium-sized star we call the sun. Our sun’s 864,000-milea diameter sounds impressive until we learn that some red supergiants have a diameter of 2,000,000,000 miles. It takes light, traveling 186,000 miles a second, eight minutes to reach earth, but it needs 100,000 years to cross our Milky Way galaxy containing some 100,000,000,000 stars.

Some astronomers estimate that there are as many galaxies in space as there are stars in the Milky Way.