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Isaac Newton: An apple a day keeps the moon in orbit
Isaac Newton publishes his universal law of gravitation in a three-volume work known as the Principia. His calculations explain the orbital motions of the Moon, planets, and comets, and allow scientists to calculate the masses of astronomical objects. A century later, two scientists apply Newton’s laws of gravity to calculate that a star of sufficient size and density could prevent light from leaving its surface, creating a ‘dark star.’ -
John Michell's dark stars
John Michell, suggests that the surface gravity of some stars could be so strong that not even light could escape from them. Using ideas about gravity and the nature of light, Michell even calculates that a ‘dark star’ the mass of the Sun would be just a few miles in diameter, which matches the modern calculations for the size of a solar-mass black hole. -
Pierre-Simon Laplace Reinvents the Dark Star
French mathematician and astronomer Pierre-Simon Laplace discovers the concept of 'dark stars' independent of Michell. He states that the 'largest luminous bodies in the Universe may be invisible.' After a new discovery about the properties of light, however, the concept is abandoned. -
Albert Einstein: It's all relative
Albert Einstein expands his theory of relativity to include the effects of gravity. His equations show that gravity is a ‘warp’ in spacetime caused by matter. The more massive an object, the greater it warps the space around it. Known as General Relativity, it provides the theoretical basis for black holes -
Faster than a speeding einstein
Before Albert Einstein can solve the equations in his own theory of gravity, German astronomer and military officer Karl Schwarzschild crafted a solution that included a startling finding: Enough matter packed into a small-enough space would have such a powerful gravitational field that nothing could escape from it, including light. -
Making (stellar) waves
Young Indian astronomer Subrahmanyan Chandrasekhar defies conventional wisdom by showing that 'heavy' stars will end their lives in a more exotic state than stars like the Sun -
Squeezing the life out of a star
A paper by Robert Openheimer who would lead the effort to develop the atomic bomb concludes that the inevitable fate of a heavy star is to collapse, cutting it off from the outside universe. -
Down the (gravitational) drain
Mathematician, Roy Kerr, shows that massive stars will ‘drag’ the spacetime around them like water swirling around a drain. Others soon realize that Kerr’s equations apply only to black holes, but that they should describe every black hole in the universe. -
More than a star, less than a galaxy
Maarten Schmidt discovers that 3c273, an odd star-like point of light known as a quasar, is one of the most powerful objects in the universe. His finding leads to the realization that it and all quasars are powered by a supermassive black hole at the center of a galaxy. -
A black hole by any other name
Physicist John A. Wheeler brings the concept of "collapsed stars" to the forefront by coining a new name for them: black holes. -
Piecing together a black hole
By combining X-ray, radio, and optical observations from telescopes in space and on the ground, astronomers identify the first possible 'stellar-mass' black hole, Cygnus X-1. -
Giving the black holes temperature
Stephen Hawking shows that black holes may not be black after all: They may emit a form of radiation that will eventually cause them to evaporate. -
Which Came First, the Galaxy or the Black Hole?
Astronomers discover that the evolution of supermassive black holes in the hearts of galaxies appears to be linked to the evolution of the galaxies themselves. The galaxies may help give birth to stars, then prevent the birth of others. -
Saggitarius A
Astronomers at the Max Planck Institute for Extraterrestrial Physics present evidence for the hypothesis that Sagittarius A* is a supermassive black hole at the center of the Milky Way galaxy -
More evidence about Saggitarius A
Further observations by a team from UCLA present even stronger evidence supporting Sagittarius A* as a black hole
