Astronomers Quiz

Aristarchus

proposed the first heliocentric model, suggested the stars were really far away, ideas were not widely accepted and were largely overshadowed by the geocentric model

Claudius Ptolemy

wrote the "Almagest" which summarized ancient Greek astronomy, introduced the concept of epicycles, defined the concept of deferents and eccentrics

Nicolaus Copernicus

proposed the heliocentric model in his work "De revolutionibus orbium coelestium.", asserted that the sun was at the center of the universe, explained retrograde motion as Eartth moving relative to other planets

Tycho Brahe

developed the tychonic system, discovered the supernova of 1572, built the Uraniborg observatory, introduced the concept of stellar parallax

Johannes Kepler

formulated the three laws of planetary motion, planets move in elliptical orbits, published "Astronomia nova", played a crucial role in confirming the heliocentric model

Gallileo Gallilei

made the first known telescopic observations of the heavens, discovered 4 moons of Jupiter, observed the phases of venus, studied sunspots, his work on inertia and falling objects laid the groundwork for Newton, faced the inquisition

isaac newton

formulated the law of universal gravitation, developed three laws of motion (inertia, F=ma, action-reaction), his work completed the scientific revolution

deferents

Large circular orbit followed by the center of the small epicycle in which a planet was thought to move

stellar parallax

the apparent shift in the position of a nearby star (relative to distant objects) that occurs as we view the star from different positions in Earth's orbit of the Sun each year

aphelion

point in a planet's orbit that is farthest from the sun

periphelion

The place in the Earth's orbit where Earth is closest to the sun.

semimajor axis

half of the major axis of an ellipse

ellipse

A elongated circle, or oval shape, the shape of the planets orbit.

eccentricity

the extent to which Mars' orbit differs from a perfect circle

epicycles

the smaller circles that the planets move in proposed by Ptolemy

deferents

the center of the epicycles moved in larger circles known as this

scientific theory

a framework of ideas and assumptions that represents our best possible explanation for something