In science, if something isn't directly observable it can't be "discovered." There is only indirect evidence of black holes. The existence of black holes has been a topic of speculation for hundreds of years, but John Wheeler is credited with coining the term, "black hole," in 1969.
The two kinds of black holes are those amongst solar masses caused by supernovae and the larger variety at the center of galaxies. Einstein predicted the existence of black holes in his general theory of relativity, published in 1916. In 1971, Cygnus X-1, an X-ray binary star, became the first object to be recognized as a black hole.Learn More
About 1,700 extrasolar planets have been discovered so far, including 715 discoveries that were announced in February, 2014 by the National Aeronautical and Space Administration. The newest extrasolar planets were discovered when astronomers examined 305 stars with Kepler, NASA's first extrasolar planet mission. Extrasolar planets, also called exoplanets, are planets that exist outside of the solar system.Full Answer >
Universe Today explains that black holes are the result of objects collapsing under the force of gravity until the acceleration needed to escape from them exceeds the speed of light. Any object can, in principle, become a black hole if it collapses to sufficient density. They can also be formed from two neutron stars colliding together. According to Universe Today, there are supermassive black holes in every galaxy.Full Answer >
According to NASA, the temperature of a black hole with the mass of the sun is only one ten-millionth of a degree over absolute zero. Scientists determine this by measuring the temperature of the radiation that comes from a black hole.Full Answer >
The universe contains three different categories of black holes: stellar, supermassive and miniature, which are further divided according to whether they are spinning. Non-spinning black holes are always spherical, while spinning black holes tend to be more oblate. The degree of equatorial bulge is determined only by the rotational velocity of the object.Full Answer >