The night sky, unimaginably deep, is a breathtaking sight. Some three thousand stars can be seen with the naked eye, twinkling points of light that have inspired the human spirit since the dawn of time. Study of the stars, based on data collected from visible-light telescopes, radio telescopes, and detectors wavelengths can now reveal extraordinary amounts of information: size, temperature, chemical composition, internal structure, distance and rotation rate, among other factors. One of the most …showed first 75 words of 1146 total…

…showed last 75 words of 1146 total…composed of 75% hydrogen and 23% helium; heavier elements make up the remaining 2%. Heavier elements, called metals by astronomers, make planets and life possible. Every atom on Earth an in out bodies was once at the center of a massive star that exploded as a supernova before the Sun and the planets formed. The shock waves from the supernova explosion are one of the mechanisms by which the interstellar medium is compressed and thus new stars formed.