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May 24, 1543
Proof of Heliocentric Theory
In 1543, Nicolaus Copernicus, a Polish cleric and mathematician, created the first geometric proof of the Heliocentric Theory. The Heliocentric Theory is the idea that the Earth and the other planets in our solar system all revolve around the sun. Though Copernicus's proof was groundbreaking in the field of astronomy, he did not publish it until his deathbed on May 24, 1543, for fear of being persecuted by the Catholic Church. After his death, the church banned all ownership of his proof. -
May 23, 1576
Uranaborg Observatory
In 1576, Danish nobleman and astronomer Tycho Brahe founded the Uranaborg Observatory. Uranaborg was built on Hveen Island, which was given to Tycho Brahe by the King of Denmark on May 23, 1576. Brahe lived at Uranaborg for 25 years, carefully taking detailed measurements of every major object in the night sky. Due to all of Brahe's observations, Uranaborg Observatory became the first astronomy database in the world. -
Johannes Kepler Becomes Tycho Brahe's Assistant
Johannes Kepler, a brilliant German mathematician and astronomer from a poor family, became Tycho Brahe's assistant at Uranaborg Observatory in 1600, when he could not find any other jobs because he did not have enough social connections. Kepler owned a copy of Copernicus's illegal proof of the Heliocentric Theory, and studied them for many years to pass the time at Uranaborg with the eccentric Tycho Brahe. -
William Gilbert Proposes that Earth is Magnetic
William Gilbert was an English physician, physicist, and philoshopher. In 1600, he published his book, "De Magnete, Magneticisque Corporibus, et de Magno Magnete Tellure," describing his theory that the Earth was a magnet with North and South poles, which is what caused compasses to always point in the same direction. He was also the first person to suggest that the Earth's core was made of iron. -
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Johannes Kepler Works On the 1st and 2nd Laws of Planetary Motion
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Kepler Discovers the First Law of Planetary Motion
Kepler's Frst Law of Planetary Motion states: The orbits of planets are ellipses with the sun at one focus. This means that planets follow oval-shaped paths around the sun at one center and empty space at the other. -
Kepler Discovers the Second Law of Planetary Motion
The Second Law of Planetary Motion states: An imaginary line connecting a planet to the sun will sweep out equal areas in equal time as the planet travels through it's orbit. This means that planets travel faster in their orbits when they are closer to the sun and slower when they are farther away, since they cover more distance in a shorter time when they are closer to the sun. -
Galileo Galilei Uses the Telescope for Astronomy
Galileo Galilei was an incredibly talented Italian Renaissance man. He was an avid astronomer, mathematician, painter, inventor, and philosopher. In 1609, Galileo came up with the idea to use the telescope, invented in 1608 by Hans Lippershey, for astronomy. Galileo observed sun spots, craters on the moon, and the four largest moons of Jupiter in their orbits. Galileo's discoveries abour craters on the moon upset the Catholic church, since they meant that heavenly bodies were imperfect. -
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Kepler Works on the 3rd Law of Planetary Motion
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Kepler Discovers the Third Law of Planetary Motion
Kepler's Third Law of Planetary Motion states: The squares of the ratio of the orbital periods are proportional to the cubes of the ratio of the average orbital distane for any two objects orbiting the same body. This means that planets closer to the sun have a shorter orbital period, or year, than planets that are farther away. -
Kepler Publishes the Third Law of Planetary Motion
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Sir Isaac Newton Discovers the Theory of Universal Gravitation
Isaac Newton was an English mathematician and physicist. In 1687, he published his Theory of Universal Gravitation, using calculus, a new type of math that he invented. The Theory of Universal Gravitation states that the force due to gravity between any two masses is equal to the ratio of gravity multiplied by mass 1 and mass 2 to the distance between the two masses squared. This means that there is a gravitational attraction between all masses, decreasing as they get farther from each other.
