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240 BCE
Eratosthenes calculated the circumference of the Earth.
They didn't have any idea how big the Earth actually was, and he estimated it. It was only 211 miles off of the true value. That is extremely impressive. He estimated it to be 24,660 miles. -
150
Claudius Ptolemy created the geocentric theory of the solar system.
People believed in this theory for hundreds of years. Almost everyone believed it, and now we know that it was wrong. He made the math work, even though he was wrong. -
1508
Nicolaus Copernicus proposed a heliocentric model of the solar system.
This was very important because we now know that this was much more accurate than the geocentric model at the time. It wasn't completely correct, but much more accurate. -
1576
Tycho Brahe built his observatory in Hven.
This enabled him to study the stars, which he did there for twenty years. The observatory let him make some of the most precise and accurate measurements of the star movements. -
Johannes Kepler created his laws of planetary motion.
This correctly described the planetary orbits. Nobody knows how the planets orbited, it was too complicated. This was revolutionary and built the grounds for Isaac Newton's work. -
Isaac Newton created his laws of gravity.
He built upon Kepler's laws and described gravity like people didn't understand. That was one of the flaws in science, and he solved it for everyone. Now they are named after him. -
Albert Einstein proposed that the laws of physics are the same throughout the universe.
This changed the way that we looked at the universe. It was an entirely new way of thinking.