Topic 7 Flashcards
(21 cards)
what is the approx. value of AU
150 million km
how far is a light year
distance light travels in a year
whats bigger: a light year or a parsec
a parsec
what % of the SS’s mass does the sun make up
more than 99%
how many years did it take voyager 2 to reach neptune
12 years as is it so far away
what were epicycles, who were they introduced by and why
-added to geocentric model by Claudius Ptolemy in order to demonstrate how retrograde motion is still possible with earth at the centre of everything
-they were small circkes in which the celestial bodies moved while simultaneously making a larger circle round the earth
what belief formed the geocentric model
the belief that the earth was the centre of the universe
what were the 2 main problems with the geocentric model
-apparent varying brightness of planets
-retrograde motion (without complex mechanics)
who proposed the heliocentric model
nicholas copernicus (16th century)
what is the function of stonehenge
used as an ancient calendar
alligned with summer solstice sunrise and winter solstice sunset
how long is a solar cycle
approx. 11 years
what 4 elements was the Aristolean Universe based on
fire, earth, air, water
what is the deferent
the larger circle which planets orbited on in ptolemy’s model
what is the equant
the centre of mass which planets orbited around (epicycles were around) in ptolemy’s geocentric model
why was copernicus reluctant to present his model to the world
religion
what did tycho observe
the motion of mars
-plotted its position systematically and precisely over 20 years
who is kepler (in relation tycho brahe)
tycho brahe’s assistant
what did brahe propose due to issues with copernican model of SS
geo-heliocentric model where moon and sun orbitted earth but everything else orbitted sun
(believed earth was too lazy to move due to religion and observation)
how did tycho die
bladder infection due to excessive drinking (some sources say mercury poisoning)
what happened with kepler after tycho died
he was free to analyse tycho’s work and noticed planets did not follow circular orbit but had elliptical orbits
-formed his 3 laws of planetary motion
what 2 discoveries were made by galileo to support the heliocentric theory
- discovery of jupiter’s main moons (4)
- venus has phases+apparent size changed
