AST 1002 Week 3 Lecture + Textbook Notes
AST 1002 Week 3 Lecture + Textbook Notes AST 1002-Section 1
Popular in Planets, Stars and Galaxies (AST 1002-Section 1, Mark Riley)
Popular in Science
This 6 page Class Notes was uploaded by Katherine Ruiz on Sunday September 18, 2016. The Class Notes belongs to AST 1002-Section 1 at Florida State University taught by Mark Riley in Fall 2016. Since its upload, it has received 77 views. For similar materials see Planets, Stars and Galaxies (AST 1002-Section 1, Mark Riley) in Science at Florida State University.
Reviews for AST 1002 Week 3 Lecture + Textbook Notes
Report this Material
What is Karma?
Karma is the currency of StudySoup.
You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!
Date Created: 09/18/16
ASTRONOMY AST 1002-0001 RILEY WEEK 3 WEEK THREE LECTURE NOTES ANCIENT ASTRONOMICAL OBSERVATIONS o Knew of Moon, Sun, Mercury, Venus, Mars, Jupiter, Saturn, meteors and stars o Stars appear fixed (this is the Celestial Sphere) o The sun was originally thought to have moved HELIOCENTRIC SOLAR SYSTEM o Copernicus (1473-1543) thought the solar system was HELIOCENTRIC o Definition: universe’s center was the sun o The planets – apparent retrograde motion o RETROGRADE MOTION occurs when Earth overtakes Mars o Johannes Kepler (1571-1630) o Developed 3 laws governing motion of planets o He was a pure theorist o Work based entirely on Tycho Brahe’s observations KEPLER’S LAWS o 1. Orbital paths of the planets are elliptical (not necessarily circular), with the sun at one focus. o SEMIMAJOR AXIS definition: § Half a major axis o Sun is one focus point, near the aphelion, empty space is the second o 2. An imaginary line connecting the Sun to any planet sweeps out equal areas in equal intervals of time o Planets that are closer to the sun move faster- this applies to comets as well! o 3. The square of a planet’s orbital period is proportional to the cube of its semi-major axis o ???? ???????? ????????????????ℎ ???????????????????? = ???? ???????? ???????????????????????????????????????????????? ???????????????????? DIMENSIONS OF THE SOLAR SYSTEM o Kepler’s law allows a scale model of the Solar System to be created o This changed everything – science took a huge step forward GALILEO GALILEI (1564-1642) o He is the father of experimental science o Creator of the TELESCOPE (1609) o Discovered the moon has valleys and craters o Discovered sunspots o The sun rotates once around its axis per month o Jupiter has moons? o Jupiter’s moons were the first objects discovered that do not revolve around Earth o Venus has phases o This makes the geocentric model impossible o Contradicted that heavens were unchanging and constant o He was put under house arrest for his discoveries by the church GIORDANO BRUNO (1548-1600) o Each star in the sky is a sun with its own planets o The universe is infinite with no center o Burnt at the stake for his proposals and discoveries ISAAC NEWTON (1642-1727) o His laws of motion explain how objects interact with the world and with each other o Earth’s gravity = general gravitational attraction between objects o NEWTON’S LAWS OF MOTION o 1. An object at rest will remain at rest and an object moving in a straight line at a constant speed will not change its motion unless acted on by an external force o Measure of an object’s inertia – mass o 2. When a force is exterted on an object, its acceleration is inversely proportional to its mass ▯ o ???? = ▯ o Unbalanced forces cause changes in motion o 3. When object A exerts a force on object B, object B exerts an equal and opposite force on A • Think ball + chimney experiment SPEED VS VELOCITY o Speed: driving 60mph o Velocity – the speed AND direction of an object’s motion o Velocity: driving 60mph east o Acceleration – A change in velocity o Measures how quickly a change in motion takes place o Acceleration is caused by unbalanced forces o Mass resists changes in motion (i.e. more mass=less acceleration) GRAVITY ▯ o ???? = 9.81 ????/???? o On Earth’s surface, acceleration due to gravity is approximately constant and directed towards the center of the Earth o Applies to ALL OBJECTS o Weight = ???? = ???????? o All objects fall at the same acceleration o Gravity is an attractive, mutual force between any two objects with mass o Astronauts float freely in a space shuttle because they’re both falling at an equal rate in Earth’s orbit o THEY’RE IN FREE FALL SPEED OF LIGHT o Electromagnetic Spectrum (EMS) o Gamma (Smallest) o X-ray o Ultraviolet o Infrared o Terahertz o Radiowave (Largest) o Sidereus Nuncius (Starry Messenger) o Most knowledge about the universe beyond Earth comes from light o Light can tell us about: o Composition, temperature, speeds, ect. o Galileo was the first to attempt to measure the speed of light o C = 300,000 km/s = 186,000 miles/s o Light is… o An electromagnetic wave o A “field disturbance” o Electric + magnetic fields o A spectrum of waves, varying wavelength and frequency o A changing electric field that prompts a changing magnetic field that prompts a changing electric field, ect. ELECTROMAGNETIC WAVES o Created by accelerating (oscillating) charged particles o Wave properties: o Wavelength: length between 2 crests o Amplitude: height of wave o Frequency: number of waves that pass in a second o Period: time to complete one cycle o Long wavelength = low frequency o THE SPEED OF LIGHT IS CONSTANT PROPERTIES OF LIGHT o Light has properties of both waves AND particles o PHOTON definition: o A particle of light o Photons carry energy and can have different amounts of energy o The higher the frequency, the more particle-like it is o The lower the frequency, the more wave-like it is ELECTROMAGNETIC SPECTRUM o Sunlight is a mixture of all colors! o Prisms DO NOT add colors to sunlight o Each color of light bends by a different amount as it passes through a prism o Objects smaller than visible light cannot be seen unaided TELESCOPES o Telescopes attempt to collect light o Intercept electromagnetic radiation o Light-gathering power is directly related to the size of the lens o Optical telescopes o Extends human sense of sight o Hubble! o Refracting telescopes o Lenses o Uses a lens to concentrate incoming light o Curved mirror concentrates incoming light at a focal point o Primary+secondary mirrors CHAPTER THREE TEXTBOOK NOTES EARLY ASTRONOMY o The geocentric model was the most prevalent model of the time because we cannot feel the Earth move o Aware that planets move in an eastward direction o Aware of APPARENT RETROGRADE MOTION o Definition: Planets would seem to turn around, move westward for a while, and then return to their eastward travel o This did not give to the geocentric model, it created problems COPERNICAN REVOLUTION o Placed the SUN at the center of the solar system, not the Earth o This creates the HELIOCENTRIC theory o FRAME OF REFERENCE definition: o A system within which an observer measures positions and motions using coordinates such as distance and time o The planets are the frame of reference for the Sun o ALL OBJECTS IN THE SOLAR SYSTEM EXHIBIT APPARENT RETROGRADE MOTION, except for the SUN o Essentially, retrograde motion is just an illusion caused by the relative motion of Earth and other objects and planets o Figured out how long it took each planet to orbit the Sun KEPLER’S LAWS o Describes the motion of the planets o The laws are EMPIRICAL o Definition: They use prior data to make predictions about future behavior but do not include an underlying theory of why the objects behave the way they do st o 1 LAW o Replaced circle with an ellipse (oval shape) o Semimajor axis is equivalent to the planet’s distance to the sun o Each orbit has its own eccentricity, which determines the shape of an ellipse. Greater eccentricity creates a longer oval o “THE ORBIT OF A PLANET IS AN ELLIPSE WITH THE SUN AT ONE FOCUS” -1 Law nd o 2 LAW o Planets move faster closer to the Sun and slower farther from the Sun o “LAW OF EQUAL AREAS-THE AREA SWEPT OUT BY A PLANET DURING A SPECIFIC TIME INTERVAL IS ALWAYS THE SAME, RndARDLESS OF THE LOCATION OF THE PLANET IN ITS ORBIT”- 2 Law o 3 LAW o The closer a planet is to the Sun, the farther its orbit is o The closer a planet is to the sun, the shorter its circumference and the faster its speed o “THE PERIOD SQUARED IS EQUAL TO THE DISTANCE CUBED”-3 rd Law GALILEO o First to use a telescope to make scientific discoveries o Experimented to prove objects accelerate while falling at the same rate, no matter the mass o BEFORE Galileo, people believed things naturally remained at rest, he proved that an object in motion will stay in motion and an object at rest will stay at rest until acted on by an outside force NEWTON o 3 laws, govern motion of every object in the universe o These laws allow connections to be made between what happens on Earth and what happens anywhere else in the universe o 1 LAW o FORCE definition: o A push or pull o Forces can cancel each other out if they are equal creating a state of no motion o INERTIA definition: o The tendency of an object to maintain its state – either of motion or of rest – until it is pushed or pulled by a net force o “DESCRIBES INTERTIA AND STATES THAT AN OBJECT IN MOTION TENDS TO STAY IN MOTION, IN THE SAME DIRECTION, UNTIL A NET FORCE ACTS UPON IT; AND AN OBJECT AT REST TENDS TO st STAY AT REST UNTIL A NET FORCE ACTS UPON IT”- 1 Law o 2 LAW o “IF A NET FORCE ACTS UPON AN OBJECT, THEN THE OBJECT’S MOTION CHANGES” – 2 Law nd o Velocity vs Speed vs Acceleration o Net forces are what cause Acceleration o 3 LAW o “FORCES ALWAYS COME IN PAIRS, AND THE FORCES OF A PAIR ARE ALWAYS EQUAL IN STRENGTH BUT OPPOSITE IN DIRECTION” – 3 Law o Action-reaction o For every force, there will ALWAYS be an equal but opposite force GRAVITY, MASS AND WEIGHT o GRAVITATIONAL FORCE definition: o The mutually attractive force between two objects with mass o Typically, the weight o GRAVITATIONAL ACCELERATION definition: o The acceleration due to gravitational force NEWTON’S LAW OF GRAVITY o INVERSE SQUARE LAW definition: o The influence of the Sun should diminish with the square of the distance from the Earth
Are you sure you want to buy this material for
You're already Subscribed!
Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'