In 1920, astronomers Harlow Shapley and Heber Curtis held a Great Debate. Shapley argued that the spiral nebulae were small ...

From tiny dust particles that slowly swirl together under the force of gravity, to distant stars that forge new elements, to the trillions of galaxies in our universe, we’ll explore the staggering ...

With this scale and other tools, Hubble had found and measured 23 other galaxies out to a distance of about 20 million light years. The second key was the work of Vesto Slipher, who had ...

The research, led by astronomer Minh Nguyen of the University of Tokyo, utilizes powerful computer algorithms that are able to compare ... of these galaxies, and hence the distance to them in ...

Subsequent advances revealed first the size of the Solar System, then the distances ... scale for the Milky Way. Well before Hubble, some people had proposed there might be a universe beyond our ...

Think of how hard it is to estimate the distance of someone pointing a flashlight at you on a dark night. Galaxies come in a very wide range of sizes and masses. Measuring a galaxy's brightness or ...