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UA / OTHER / ay 101 / What does a heliocentrist believe in when it comes to astronomy?

What does a heliocentrist believe in when it comes to astronomy?

What does a heliocentrist believe in when it comes to astronomy?


School: University of Alabama - Tuscaloosa
Department: OTHER
Course: Intro to Astronomy
Professor: Ronald buta
Term: Spring 2017
Tags: astronomy, Astronomy 101, intro to astronomy, history, newton's laws, and Astronomers
Cost: 25
Name: AY 101 Week 5
Description: These notes address the history of astronomy, such as famous astronomers and their accomplishments. This also covers a few laws that such astronomers created, like Newton's laws of motion.
Uploaded: 09/17/2017
4 Pages 42 Views 4 Unlocks


What does a heliocentrist believe in when it comes to astronomy?

∙   Geocentric to Heliocentric

o Geocentric view of the Universe means the Earth is the center o Heliocentric means the Sun is the center

∙   Astronomers

o Aristotle

 Geocentrist

 “perfect” shapes and motions in celestial objects; he believed everything in the sky was a perfect circle and sphere

 Believed the earth and sky were separate

 Believed stars, moon, planets, etc. were on concentric spheric planes of “aether”

 Believed matter naturally rested

 Mixed observation and theory

What is copernicus' contribution in astronomy?

o Artistarchus

 Heliocentrist

 (310-230 BC)

 Believed sun was bigger than the Earth and that it would make sense for the smaller object (Earth) to orbit the bigger object (sun)

∙    Realized sun was farther away b/c of the moon phases, so since sun and moon seem the same size,

the sun must be huge

 Not accepted in his time

o Eratosthenes

 (273-195 BC)

 Measured Earth’s radius to a 2% error

 Determined the difference of the angle of the sun in two different locations and used it to create a proportion to figure out the radius

Who founded the three laws of motion?

o Ptolemy

 (85-165 AD

 Geocentrist

 Added epicycles to orbits to account for retrograde motion  Gave Venus phases “new and cresent” We also discuss several other topics like How is basal metabolic rate different from standard metabolic rate?

o Copernicus

 (1473-1543)

 Heliocentrist

 Clergyman

 Still believed in perfect circles, but made the sun the center to simplify the models of the universe and because it was aesthetically pleasingDon't forget about the age old question of Which evidence of evolution refers to similarities as a result of common ancestry?

 Refused to publish his work until after he died because he did not want to be ridiculed We also discuss several other topics like Which scientific study refers to how thoughts, feelings, and behavior are influence by the actual or imagines presence of others?

o Tycho Brahe

 (1546-1601) We also discuss several other topics like Which amendment formally outlaws slaves throughout the us?

 Geocentric

 Very rich, owned much land, close with king of Denmark  Built massive observatory

 Lost half of his nose in a duel over a math problem, had an alcoholic pet moose

 Had to go to the bathroom while visiting the king but wanted to be polite, so he held it and his bladder burst and he got an infection and died

 Discovered a supernova

 Collected massive amounts of data

o Johannes Kepler

 (1571-1630)

 Heliocentrist

 Accurate planetary orbital laws

 Assisted Brahe We also discuss several other topics like What are some proposed solutions to a free-rider problem?

 Tried using perfect circles, but when it failed, finally went to ellipses; some planets were more elliptical than others  3 orbital laws If you want to learn more check out What is the difference between dopamine and serotonin?

∙    Planets are in elliptical orbits around the Sun with the Sun at one focus of ellipse; sun was in the small side of more elliptical orbits, not directly at center

∙    Sun-planet line sweeps out equal areas in equal time; orbital speed not uniform; faster when closer to sun due to gravity

o Equal spaces of time within an orbit; distance

traveled when made into a triangle with the

sun, area the same in all triangles

∙    Period2 is proportional to distance3; so p2=a3 

o Mass, size, etc. does not affect rotational


 His work was a turning point in astronomy

 No physics behind his laws, just mathematical fits (didn’t understand gravity)

o Galileo Galilei

 (1564-1642)

 Physical laws

∙    Law of Inertia: objects at rest tend to stay at rest, or objects in “uniform motion” tended to stay in motion

o Inertia: resistance to change in motion; more

mass=more inertia

∙    Different masses fall at same rate

 1st astronomical use of the telescope; discovered: more stars; Milky Way, fuzzy patches made of stars; Moon is blemished by mountains, craters, dark patches; Jupiter’s moons; Saturn is not a sphere; sunspots; supernova; phases of Venus, sometimes full disk

∙    Most of these discoveries revealed flaws in Greek astronomical beliefs; imperfections in spherical-ness of planets and sun and moon, also saw Jupiter had moons, which goes against the idea that everything orbits earth, also full phase of Venus proved Venus orbits the sun

 Believed in Copernican heliocentric theory, not Kepler’s  Spent the last part of his life in house arrest until his death because he was thought to be a heretic

o Isaac Newton

 (1642-1727)

 Most of his discoveries came during the 2 years he stayed home waiting for the plague to dissipate

 Professor of Math at Cambridge University

 Co-founded Calculus, his version was complex and difficult  Named Master of the Mint in London, decided to have counterfeiters executed

 3 laws of motion

∙    1st Law: Law of Inertia: “Objects remain at rest or in uniform motion unless acted upon by forces.”

o Also applies to planets and moons

o Newton’s cannon: if a cannon ball was

launched with a fast enough velocity, it could

orbit the earth; he realized this could also

apply to the moon, and therefor realized that

earthly physics also applies to celestial physics

∙    2nd Law: F=ma (force equals mass times acceleration)

o a=F/m (acceleration equals Force divided by


o acceleration=change in velocity over time

o accelerations are caused by forces

o Contact forces: friction, tension, “normal”

forces, impacts, spring forces, air/fluid

resistance, pressure differences

 All of these are a type of


o Fundamental Forces: Gravity, Electromagnetism, Weak nuclear force (sub nuclear), Strong nuclear force

o Speed-change in position over time

o Velocity-speed in relation to direction

o Acceleration-change in velocity over time

∙    3rd Law: for every action, or force, there is an equal and opposite reaction

∙    Law of Gravity: everything is attracted to each other through the force of gravity; the force of gravity is proportional to the mass of each object and inversely proportional to the square of the distance

o Explained Galileo’s principle that despite differences in mass, objects would land at the same time

o Fgrav=g*m1*m2/r2 (g=gravitational constant, 6.674×10 N⋅m²/kg²; m1 and m2 are masses of two separate entities; r is the distance between the two entities)

o Acceleration due to gravity depends only on the mass of the object the falling object is being pulled toward

 Newton’s laws explain Kepler’s Laws

∙    (M+m)=(4π2/G)*distance3/period2 


∙    Mass is measured by the matter within something (always stays the same); weight is a force caused by gravity acting upon mass (depends on amount of gravitational pull)

∙    Weight on the Moon is 1/6 of that on Earth

∙    You can feel “weightless” when gravity is very weak where you are, or when you are being pulled by strong gravity but feeling no resistance.

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