Essay on Astronomy 2 Notes

Submitted By Benyamin2
Words: 1476
Pages: 6

* The five naked eye planets 1. Mercury 2. Venus 3. Mars 4. Jupiter * Direct and retrograde motion
Planets are brightest during retrograde motion
Epicycles and deferent
The Ptolemaic explanation for retrograde motion
The geocentric cosmology of Ptolemy (100-170 AD)
The Copernican explanation for retrograde motion * Nicolai Copernicus (1473-1543)
The Heliocentric cosmology
Inferior and superior planets * Tycho Brahe (1546-1601)
Made detailed observations of planetary motion * Johannes Kepler
The empirical method * 1st law: the orbit of a planet is an ellipse with the sun at the focus * 2nd law: an imaginary line joining the sun and a planet sweeps out equal areas in equal times. * 3rd law: the harmonic law p2=a3 p= orbital period (earth years) a= semi-major axis (AU) a is also equal average distance of the planet and sun the further the planet is from the sun, the longer it takes to orbit
Galileo was one of the first people to study the sky with a telescope

The Phases Of Venus can only be explained if Venus orbits the sun * The inquisition of Galileo (1616) A. Isaac Newton (1642-1727) i. The analytical method 1. 1st law: an object will remain at rest or move in straight line at constant speed unless a force acts 2. 2nd law: a. f=ma i. f= force applied ii. a= resulted acceleration mass = measure of total amount of matter weight = force exerted by mass due to gravity 3. 3rd law: action and reaction are equal and opposite ii. Newton’s universal law of gravitation 4. F= GM1M2 * d2
G is a constant (does not change ) can be ignored during analysis

inverse squared iii. dx2 Fx1/2^2=1/4 iv. dx3 Fx1/3^2=1/9 proof of Kepler’s 3rd law
Newton’s modified form
P(2)=a(3)/m(1)+m(2)
kepler only deduced an approximation
Sir Edmund Halley (1656-1742)
Halley’s Comet
Adoration of the Magi- Giotto (1304-6)
Inspired by Halley return in 1302?
The planet Uranus
Discovered telescopically in 1781
The planet Neptune
Discovered by gravitational calculations in 1846

I. Newton’s Experiment A. Light is made up of different colors B. Light behaves like a wave 1. Wave- like properties of light wavelength * Visible light ^ =4-7 x 10(-7) m 2. Units of wavelength
I nanometer(nm) = 10(-9) m
1 angstrom = 10 (-10) m 3. Interference C. Properties of electromagnetic radiation 1. Carries information 2. Not just visible 3. Very fast- 3x10(8) m/s 4. Travels through a vacuum D. High energy – high frequencies and short wavelengths E. Low energy – low frequencies and long wavelengths 4. C= speed of light = constant 1. Wave length x frequencies gives you the distance light is going

all matter produces EM radiation variations temperature is related to atomic and molecular motion low movement = low pressure high movement = high pressure
The Kelvin Scale
Temperatures measured relative to absolute zero (0 K)
Absolute zero is fixed
More reliable temperature measurement
Cool matter – temperature (down) speed (down )
Absolute zero – at -273 Celsius or -460 Fahrenheit atomic and molecular motion essentially stops
Relationship between Kelvin and Celcius scales
T(k) = T(C)+273
T(C) = T(K)-273
Objects change when they are heated
Color changes
Wiens Law
K= constant T = temperature max = dominant (strongest wave length )
Intensity changes
Stefan’s Law
F= T(4)
F= flux (total energy emitted to all wave lengths ) = constant T= temperature
T(up) F (up)
Blackbodies
1. Objects which obey the radiation laws exactly 2. Absorb all radiation,…