Tycho Brahe (1546–1601) was a Danish astronomer. When he was 20, Brahe lost part of his nose in a sword duel with his third cousin, Manderup Parsberg. Manderup’s blade cut away most of the nasal bridge, leaving the nasal cavity and septum exposed.

Galileo became completely blind by the age of 74, but NOT because he looked at the Sun through his telescope. He always projected an image of the Sun onto a surface. Remember, like Galileo, you should NEVER look directly at the Sun! Galileo’s telescopes had a magnification of only about 30x.

What was Tycho Brahe’s greatest contribution to astronomy? He first used the telescope to make extensive astronomical observations. He determined that the planets orbit the Sun in elliptical orbits. He proposed some simple laws that govern the motion of the planets and other objects.

Nove

Brahe believed in a model of the Universe with the Sun (rayed disk) orbiting the Earth (black dot), but the other planets (symbols) orbiting the Sun. In an attempt to prove his theory, Brahe compiled extensive astronomical records, which Kepler eventually used to prove heliocentrism and to calculate the orbital laws.

Aristotle’s model of the universe was also geocentric, with the Sun, Moon, planets, and stars all orbiting the Earth inside of Eudoxus’ spheres. Aristotle believed the universe is finite in space but exists eternally in time.

current best fit model

Aristotle, who lived from 384 to 322 BC, believed the Earth was round. He thought that each space body moved in a small circle (an epicycle) that was itself orbiting Earth. This explained why planets sometimes appeared to travel backward in the sky.

The Moon is farthest from the center in all three systems!!!

The second-known interstellar object – identified as a comet and labeled 2I/Borisov – reaches its perihelion, or closest point to the sun, on December 8, 2019. At this distance, it’s about twice as far as from the sun, just outside Mars’ orbit. Comets are most active when they’re nearest the sun.

Neptune

Pluto and Neptune orbits are not in the same plane. Jason asks: “Since Pluto’s orbit intersects Neptune’s orbit, will Pluto ever crash into Neptune or become one of Neptune’s moons?” Answer: No. From 1979 to 1999, Pluto was the eighth planet from the sun.