Lesson 2: Vocabulary Flashcards
Heliocentric
Sun centered universe.
Configuration
Geometrical arrangements of the planets.
Superior Conjunction
When an inner planet is in the opposite side of the sun.
Greatest Western Elongation
The farthest west a planet reaches.
Conjunction
When a planet is lined up directly behind the Sun.
Aristotle
Proposed a theory of the universe that entailed two types of motion: towards/away from and around.
Retrograde Motion
When a planet appears to stop, move backwards, and then start moving forward again.
Epicycles
Spheres within spheres. The smaller sphere.
Ptolemy
Able to predict the exact location of the planets by using epicycles in Aristotle’s theory.
Aristarchus
Proposed the heliocentric theory-a sun centered universe.
Geocentric
An earth centered universe.
Eratosthenes
Calculated the circumference of the earth.
Copernicus
Determined the order of the planets and detailed the advantages of a heliocentric cosmology.
Inferior Conjunction
When an inner planet is lined up between the earth and the sun.
Greatest Eastern Elongation
A planet is as far east of the Sun as it can be.
Opposition
The planet is on the opposite side of the earth (from the Sun).
Period
The amount of time it takes to complete one revolution.
Synodic Period
The time that elapses between two successive identical configurations.
Sidereal Period
The true orbital person of a planet.
Kepler
First scientist to propose that planetary orbits are not circles.
Ellipse
A curve shaped like an oval; planets revolve around the Sun in these.
Kepler’s First Law
The planets orbit the Sun in an ellipse with the Sun at one focus.
Perihelion
A planet moves more rapidly when it is nearest the Sun.
Aphelion
A planet moves more slowly when it is farthest from the Sun.
Kepler’s Second Law
A line joining a planet and the sun sweeps out equal areas in equal intervals of time.
Kepler’s Third Law
The squares of the sidereal period of the planets are proportional to the cubes of the semi major axes of their orbits. (P^2 = a^3)
Galileo
First person to use the telescope, discovered that Venus has phases, Jupiter has moons, the Sun has spots, and saw mountains on the Moon.
Newton’s Law of Inertia
An object at rest or in constant motion will remain that way unless acted upon by an unbalanced force.
Newton’s Law of Acceleration
The acceleration of an object is proportional to the force acting on it. (F = ma)
Newton’s Law of Reactions
For every action force, there is an equal and opposite reaction force.
Newton’s Law of Universal Gravitation
Fg = (Gm1m2)/(d^2)
Einstein
Proposed a theory called general relativity.
General Relativity
Gravity was not a force, but rather “curved space”.
Gravitational Lensing
The curvature of space (gravity) actually bends the path of light.
Deferent
The larger sphere in an epicycle.
