We have known for some time that the universe is expanding, and that its expansion is accelerating. But how do we know that? We'll show you how Edwin Hubble revealed that the universe is getting away from us.
This is Palomar 2, one of 15 globular star clusters originally discovered by Hubble—not the space telescope, but its legendary namesake, as Edwin Hubble was part of the project that first discovered these clusters back in the 1950s.
This star may not look like much, but in 1923 it changed our understanding of the universe forever. It showed us that the Milky Way wasn't a lonely island universe, but instead just one of billions and billions of galaxies.
From Darwin and Einstein to Hawking and Sagan, here are twenty-five amazing books written by world-famous scientists. These are legendary texts, popular science explainers, personal memoirs, and controversial new theories, and they're all enduring monuments to the power of science.