AST 1002 Exam 1 Study Guide Rene Descartes I think therefore I am I observe the essence of science We can observe things on earth and use it to observe things in space because physics are the same throughout the universe Occam s Razor says that out of two theories that the same thing pick the simpler one Galileo Galilei embraced the new telescope and discovered Venus s phases which led to Geocentric theory proven to be false Tycho Brahe Kepler Brahe was some rich guy who took up star gazing and he recorded everything he saw Then he hired Kepler to analyze the data which he used to make up three laws known as Kepler s Laws 1 The orbital paths of planets are elliptical with the Sun at one focus Perihelion a 1 e point with the shortest distance from sun Aphelion a 1 e greatest distance from sun Major Semi Major Axis long horizontal distance from Perihelion to Aphelion and the Semi Major is just half of the Major Minor Axis vertical distance Eccentricity how circular the ellipse is perfect circle 0 eccentricity 2 While orbiting the sun 2 imaginary lines go out from the sun to 2 points of the ellipse creating a triangle type of shape All of these shapes are equal in area at equal times No matter if they are closer to the perihelion or aphelion 3 The square of a planet s orbital period is equal to the cube of its semi major axis Equation P2 a3 This is how we find the period of orbit Angular Momentum and its speed decide our orbit and prevent us from falling into the sun much like how water stays in a bucket as you swing it around Equation L rmv ex rotation of the Earth spin or revolution of Earth around the Sun orbital motion Isaac Newton came up with a model demonstrating how all objects interact with each other and developed the 3 laws of motion Newton s Laws of Motion and 1 of gravity Motion force changes it 1 An object at rest stays at rest and an object in motion stays in motion until an external 2 Acceleration of an object is proportional to the net applied force and inversely proportional to the object s mass Equation F ma ex Two students on rollers fat student A pushes skinny student B and B goes off as A stays relatively still with perhaps a slight movement backwards 3 To every action there is an equal and opposite reaction Gravity 1 Every particle of matter attracts every other particle with a force directly proportional to the product of the masses of the particles and inversely proportional to the square of the distance between them Newton s Law of Universal Gravitation Equation F G M 1 M 2 r2 Newton s constant G 6 67 10 11 N m2 kg2 Light can be described as either a electromagnetic wave or a particle The speed of light know as c is approximately 3 0 x 108 m s in a vacuum There is nothing faster Mediums slow down the speed of light and other waves Doppler Shift is the shift of light which shows the motion relative to us of very far away objects Equation vr obs rest rest c Temperature The temperature of an object is directly related to the amount of microscopic motion within it The SI unit for temperature is the Kelvin Blackbody Curves The given temperature of an object provides a different spectrum of emitted radiation with the peak given by Wien s Law Telescopes There are 2 basic types Equation peak 2900 m K T 1 Refracting use lenses to bend beams of light much like Galileo would have made 2 Reflecting use curved mirrors to collect and concentrate light which avoids chromatic aberration problem with refracting telescopes Diffraction Limit the amount we are limited to seeing objects based on resolution because of diffraction Equation 2 06 105 D Star Formation Large clouds of dust and gas begin to come together due to gravitational force and when they are dense and cool enough hydrogen and other atoms form molecules These are called Molecular Clouds Sometimes if these are big enough they will collapse under their own gravity and eventually create Molecular cloud cores near the center When these get denser and hotter from the continual collapse on themselves the result is a protostar Protostars are way brighter than our Sun but not in the visible light spectrum Oddly before they can collapse any further they must cool down first by emitting radiation that escapes the cloud From there it could either fail and become a Brown Dwarf like Jupiter or it could succeed by having enough mass density and pressure to start a nuclear reaction where hydrogen is converted to helium and BOOM Star Planet Formation ignoring the inner part of the cloud we can focus on the outskirts or protoplanetary disk were planets are made Particles of dust and gas are all spinning around and crashing into one another until large clumps are made and that s when gravity starts to help them out by attracting more clumps and particles to them until Planets
View Full Document
Unlocking...