Unit 2 Solar System Discoveries Flashcards
Who was Copernicus?
Copernicus was a Polish astronomer who developed the first heliocentric model of the Universe. He lived in the 16th century where it had been believed since Ptolemy (Egyptian) that the Universe was geocentric.
What was Copernicus trying to explain?
Why we saw retrograde motion of Mars, Jupiter and Saturn.
Who was Tycho Brahe?
A danish astronomer who mapped the skies with unprecedented precision in the 16th century.
Who was Johannes Kepler?
Tycho Brahe’s assistant who continued his observations and made his laws of planetary motion.
What do Kepler’s First and Second Laws state?
First: Planets move in elliptical orbits around the Sun with the Sun at one focus or the ellipse.
Second: Relates a planet’s speed to its distance from the Sun: “An imaginary line from a planet to the Sun sweeps out equal areas in equal intervals of time.”`
What is Kepler’s Third Law?
T^2=R^3
When:
T is orbital period around the Sun in years.
R is the planet’s mean distance from the Sun in AU.
Who was Galileo Galilei?
Galileo Galilei was an Italian astronomer who used the recently invented “optick tube” (telescope) to view the skies and make sketches.
Give examples of some of Galileo’s discoveries.
The Moon was not spherical it contained hollows and protuberances (craters and mountains).
Venus goes through phases like those of the Moon but on a timescale of weeks.
Jupiter had four satellites: Castillo, Europa, Ganymede and Io.
Who was Isaac Newton?
Isaac Newton was an English mathematician who published Principia in 1687. In Principia he states that the gravitational force of attraction between two bodies is dircetly proportional to the product of their masses and inversely proportional to the square of the distances between them.
What is the inverse square law?
If the distance between two objects doubles, the force is one quater of it’s previous value as on quater is the inverse of 2 squared.
Who discover Uranus?
William Herschel in his garden in Bath. He first mistook it as a comt through his telescope but after more observations he found it to be a planet.
Who discovered Ceres?
Ceres was discovered by Italian astronomer Giuseppe Piazza. Originally it was a new planet, but was later named an asteroid, however now it is a dwarf planet.
Who predicted Neptune’s existence?
Neptune was predicted independently by Englishman John Couch Adams and Frenchman Urbain Le Verrier. They predicted its existence due it irregularities in Uranus’ orbit. Johann Encke was informed then two of Encke’s assistants, Johann Galle and Heinrich D’Arrest, discovered the new planet and named it Neptune.
How was Pluto discovered?
Photographically during 1930 by Clyde Tombaugh at the Lowell Observatory in Arizona. This was due to American astronomers Edward Pickering and Percival Lowell suggesting (incorrectly) that another undiscovered planet was affecting Uranus’ motion.
