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Intro to Galaxies & Cosmology
trippy
24
Astronomy
Undergraduate 2
02/09/2009

Additional Astronomy Flashcards

 


 

Cards

Term
Light year
Definition
distance that light travels in one year
Term
Speed of light
Definition
3 x 10 ^ 8 m/s
Term
Parsec
Definition
3.26 light years (average distance between stars)
Term
AU
Definition
150 million km, distance between the earth and the sun
Term
Newton's first law of motion
Definition

A body in motion tends to stay in motion (inertia)

 

Objects travel in a straight line unless compelled to do otherwise.

Term
Newton's second law of motion
Definition

An unbalanced force on an object causes acceleration

 

Force = mass x acceleration

Term
Newton's third law of motion
Definition
For every action, there is an equal and opposite reaction
Term
Principia Mathematica
Definition

1687

 

Explained reasons behind Kepler's observations and laws

 

Presented the law of gravity

 

created modern physics

 

 

Term
Newton
Definition

Architect of modern science

 

Merged math and science which made it possible for facts and claims to be proved wrong.

 

Being able to disprove hypotheses allows us to build on science and make PROGRESS.

Term
Newton's Law of Gravity
Definition

attractive force acting in a line between 2 objects

 

proportional to the mass of one object times the mass of the other

 

inversely proportional to the square of the distance between their centres

 

(gravity is higher between closer objects)

Term
Plato
Definition

most perfect geometric shape = sphere, uniform circular motion

 

human observations should not be trusted

 

universe is perfection

Term
Aristotle
Definition

REASON

 

universe divided into changeable, corrupt worth and perfect, unchanging heaven.

Term
Aristarchus
Definition
first astronomer to believe in a heliocentric model of the universe
Term
Ptolemy
Definition

retrograde motion of planets

 

"epicycles"

Term
Nicolaus Copernicus
Definition
heliocentric!!
Term
tycho brahe
Definition

extremely accurate instruments to measure astronomy

 

discovered new stars (nova) --> universe is NOT unchanging

Term
Johannes Kepler
Definition

empirical laws based on Brahe's observations

 

(Brahe never asked WHY his ideas worked)

 

 

Term
Kepler's 1st law of planetary motion
Definition
Planets move on elliptical orbitcs with the sun as one focus
Term
Kepler's second law of planetary motion
Definition
Planets sweep out equal area in equal time
Term
Kepler's 3rd Law of Planetary Motion
Definition

the square of the period of a planet's orbit equals the cube of the semi-major axis of the orbit

 

period ^2 = semimajor axis ^3

Term
Force of gravity
Definition

F = G x mass of object1 x mass of object2/

distance between them^2

Term
velocity
Definition

2 x pi x radius of the circle/

time or period of the orbit

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