A Brief History of Astronomy Flashcards
the Earth is the center of the universe and all other heavenly bodies revolve around it
Geocentric Model
the Earth and other planets revolve around the Sun
even some Early Greeks already believed this!
Heliocentric Model
one of the Greek philosophers who believed in a spherical Earth
Parmenides
gave scientific credibility to the idea of a spherical Earth
using the shadow cast by Earth on the Moon, which is round
Aristotle
credited for establishing the circumference of the Earth
using the angles of the Sun’s rays at noon in two Egyptian cities
Eratosthenes
known for significant contributions to astronomy
including trigonometry, distance between Moon and Earth, length of a year
Hipparchus
a geocentric model of the universe accounting for the apparent motion of the planets as it revolves around a stationary Earth
created by and named after Claudius Ptolemy
Ptolemaic System
Polish astronomer who advocated for a heliocentric universe model
the Copernican system
Nicolaus Copernicus
Danish astronomer who aimed to refute the Copernican system
Tycho Brahe
German astronomer who formulated the three basic laws of planetary motion
despite working as assistant to Brahe, he believed in the Copernican system
Johannes Kepler
all the planets move around the Sun in an elliptical orbit
Kepler’s Laws of Planetary Motion
Law of Ellipses
if you trace an imaginary line from a point in the orbit to the Sun as the planet revolves, the line sweeps over equal areas in equal time intervals
Kepler’s Laws of Planetary Motion
Law of Equal Areas
a point where the planet’s orbit is closest to the Sun
Law of Equal Areas
Perihelion
a point where the planet’s orbit is farthest from the Sun
Law of Equal Areas
Aphelion
the square of a planet’s orbital period is proportional to the cube of a planet’s mean distance to the Sun
Kepler’s Laws of Planetary Motion
Law of Harmonies
Italian astronomer who discovered the surface of the Moon, Jupiter’s four moons, and sunspots
Galileo Galilei
prominent English scientist who found the answer to the question of what kept planets in orbit instead of floating away in space
Sir Isaac Newton
everybody in the universe attracts every other body with a force proportional to the mass of the bodies and inversely proportional to square of the distance between the bodies
Law of Universal Gravitation
F = Gm1m2/r^2
gravitational constant/universal gravitational force
6.67 x 10^11
