The Tychonic Model

1610
- Galileo's use of the telescope heralds a revolution that eventually supplants astronomy observed with the unaided eye.
1620
- Kepler finishes formulating his laws of planetary motion.
1670s
- All of Europe's capital cities have large observatories built.

In the 16th century, the planet’s orbit is a huge mystery.
Tycho Brahe required precise observation in order to solve the mystery and prove something.
In 1562, the conjunction of Jupiter and Saturn occurred days earlier than predicted by the best available astronomical tables.
- He seized the opportunity to observe and measure the planet's paths.
In 1572, a bright new star appeared in the sky, in the constellation Cassiopeia, and remained visible for 18 months before fading from view.
- Tycho determined that the new object was not an atmospheric phenomenon but a real star after carefully measuring it and finding that it did not move in relation to nearby stars.
- The supernova remnant, known as Cassiopeia B, is still observable in the sky today — which was later determined to be a supernova.

Tycho set out to build a system of armillary spheres, quadrants, and sextants that could measure the position of a planet in the sky with an accuracy of about 0.5 arcminutes.
Over the course of about 20 years, he measured the positions of the planets himself.
At his observatory on Hven, Tycho meticulously measured the star positions and noted them on brass plates on a spherical wooden globe with a diameter of about 5 ft 3 inches.
His globe had about 1,000 stars recorded on it by the year 1595. It could rotate around a polar axis, and a horizontal ring was employed to help distinguish between stars that were above and below the horizon at any given time.
In 1728, the globe that Tycho traveled with was destroyed in a fire in Copenhagen, Denmark.
Tycho noticed that the comet appeared to be moving freely and came to the conclusion that the spheres were impossible.

Tycho was also highly intrigued by Copernicus' heliocentric model.
If Copernicus was correct, nearby stars would appear to move in tandem with Earth's annual orbit of the sun, a phenomenon known as parallax. Tycho looked everywhere but was unable to locate any stellar parallax.
There were two likely outcomes:
- Tycho couldn't measure the change in the stars' positions with the tools available at the time because the stars were too far away.
- The Earth did not move and Copernicus was mistaken.

The Tychonic model placed Earth at the center of the cosmos, but the five known planets now orbited the sun. Despite his admiration for the Copernican model, Tycho believed that the Earth did not move.
He didn't feel the Earth in motion. He was not persuaded by anything he saw that the planet was moving. The universe outside seemed to be the only thing in motion; Earth seemed to be stationary.
After Tycho's death in 1601, astronomers who were unhappy with Ptolemy's Earth-centric system but did not want to offend the Catholic Church by adopting the outlawed Copernican model continued to favor it for many years.
Tycho’s thorough observations enabled Johannes Kepler to establish the elliptical nature of the planets' orbits and to develop a model that would supersede both the Tychonic and Copernican models.
Edmond Halley, an English astronomer, learned about the proper motion of stars in 1718 thanks to Tycho's improved measurements.
- He observed that the bright stars Sirius, Arcturus, and Aldebaran had shifted by more than a half degree from their positions when Hipparchus made his observations 1,850 years earlier.
- Not only were the stars not fixed in the sky, but it was also possible to measure how the closer stars were moving.
- Only in 1838 was stellar parallax discovered.

Tyge Ottesen Brahe — was born a nobleman in 1546 in Scania.
His observation of a predicted solar eclipse in 1560 led him to pursue a career in astronomy.
King Frederick II granted Tycho the island of Hveen in the Oresund, Strait in 1575, on which he constructed an observatory.
Tycho later closed the observatory after a disagreement with Christian IV, Frederick's son and successor, regarding the possible transfer of the island to his children.
He was appointed Imperial Mathematician to Emperor Rudolph II in Prague in 1599.
Tycho appointed Johannes Kepler as his assistant there.
Tycho was well known for having a distinctive metal nose that was the result of a duel he had in school.
He passed away in 1601, allegedly from a ruptured bladder, after politely declining to use the restroom during a lengthy royal banquet.