AST MT Notes PDF

TOUR Orbit Summary - - - - - Terrestrial Planets Small, rocky, thin/no atmosphere, few moons, heavy elements MERCURY, VENUS, MARS, EARTH Mark very viciously entered Mercury - - - - Venus - - - - - Earth - - - Mars - - - Jovian Planets JUPI...

TOUR Orbit Summary - - - - - Terrestrial Planets Small, rocky, thin/no atmosphere, few moons, heavy elements MERCURY, VENUS, MARS, EARTH Mark very viciously entered Mercury - - - - Venus - - - - - Earth - - - Mars - - - Jovian Planets JUPITER, SATURN, URANUS, NEPTUNE Justin saw us near..... Jupiter - - - - Saturn - - - - Uranus - - - Neptune - - - Earth\'s moon - - - - Comets - - - The Earth\'s Rotation Seaons Summer - Daylight is longer and Darkness is shorter - Winter- Daylight is shorter and darkness is longer - Constellations - Astronomy has failed claims, but many people believe them to be true. THE MOON - - - - - The correct answer is **e) None of these**. Here\'s why: - - - New Moon - - - - Waxing crescent - - - - Waxing Quarter - - - - - Waxing Gibbous - - - - Full moon - - - - - Waning Gibbous - - - - Waning quarter - - - - Waning crescent - - - - Solar eclipse - - - - The Heliocentric Solar System The Geocentric Universe - - Retrograde motion - - - - Kepler - - - Galileo - - Newton\'s Laws Speed - the rate of change of position Velocity- speed and direction CAR DUE NORTH AT 60km/hr Acceleration- the rate of change of velocity 1st law- An object in motion remains in motion unless acted upon by outside force 2nd law- Acceleration is proportional to force and inversely proportional to mass More force more acceleration More mass less acceleration 3rd law- For every force there is a equal and opposite reaction force Momentum Mass x velocity Angular momentum- mass x velocity time distance In astronomy, **angular momentum** refers to the quantity of rotational motion an object has around a point, typically a star or planet. It\'s a conserved quantity in orbital mechanics, meaning it stays constant unless acted on by an external force. Newton\'s Universal Law of Gravitation - - - - Acceleration due to gravity - - - Freefall - - Tides Escape velocity - The minimum velocity with which an object can escape the gravitational pull of the plane Gravitational attraction between earth and the moon applies force The varying gravitational force squeezes both the earth and the moon Earth is rotating to fast for rock and mantle to respond much Tidal locking - - - - The sun also causes tidal forces on earth - - Structure and Energy Generation Why does sun shine? What is the Suns structure How does nuclear fusion occur in the sun How do we know what is happening inside the sun Basic properties - - - - The core - Radiative zone - - - - Convective zone - - - - Photosphere - - - Sunspots - - - The chromosphere - - - The Corona - - Squeezing gas makes the sun hot Atoms - - Molecules - - Chemical reactions - - Nuclear reactions - - Nuclear fission vs fusion Fission - requires heavy elements like uranium, plutonium Fusion- uses light elements like hydrogen and helium Very hard to make happen because protons fiercely repel unless they get very close Sun is made up of reactions therefore is loses mass(Around 4 tonnes every second) Fusion only happens in the core Why is the sun stable ? Balance between radiation pressure exerted outwards (causing burning) and gravitational pressure inwards/outwards collapse\>hydrostatic (gravitational equilibrium) How does nuclear fusion occur in the sun H+H+H+H \> He+Energy The Solar Spectrum Posistron- Like an electron, but with positive charge Neutrino- Very low mass Gamma ray- type of light Waves (I) A wave describes 3 things - - - Waves (II) Speed = wavelength x frequency Ex Wavelength = 2 meters Frequency = 3 peak per sec So Speed = 6 meters per sec At constant speed, shorter wavelengths have higher frequencies Light is a wave - - - - - - Spectrum of light - - - - Blackbody Radiation - - - - - Spectrum Laws - - Emission vs Scattering In the context of light, **emission** and **scattering** are two distinct processes that describe how light interacts with matter: ### **Emission:** - - - - - ### **Scattering:** - - - - - ### **Key Differences:** - - These concepts are important in understanding phenomena like how stars shine (emission) and how light behaves in the atmosphere (scattering). How do we experience light? Radiative energy How do light and matter interact? Emit, absorb, transmit, reflect/scatter What is light? Electromagnetic wave What is the electromagnetic spectrum? The various forms of light, which are based on wavelength/frequency/energy The solar Spectrum and Emission Lines Atoms (I) - - - - Phases of matter - Solid - Atoms or molecules are held in rigid structure Liquid - Atoms or molecules are stuck together, but can change their positions Gas - Atoms or molecules move around independently (surface of sun) Plasma - When a material is very hot, the electrons separate from the nucleus (interior of the sun) Light is a wave particle - - - Each photon of a given color (or wavelength, or frequency) carries exactly the same energy - - Atomic Energy Levels - - - Absorption Lines - exactly to the energy change - Energy Levels of Hydrogen Simplest case Hydrogen atoms - - - Specific series of absorption lines (if background light is provided) Every atom has unique set of energy levels and hence a unique spectral fingerprint Lights tell us... - - The Doppler Effect Ripples - - The Doppler Effect sound - - - The Doppler Effect for light - - - - - The Doppler Effect for light: Spectra  What is the structure of matter? - Protons and neutron in a nucleus surrounded by electrons What are the phases of matter - Solid\>liquid\>Gas\>Plasma How is energy stored in atoms? - Orbits of electrons What are three basic types of spectra- Continuum, absorption, emission How does light tell us: - - - ELECTRONS CAN BE FORCED TO JUMP TO A HIGHER-ENERGY ORBITAL BY ABSORBING LIGHT ELECTRONS CAN SPONTANEOUSLY DEIO TO A LOWER-ENERGY LEVEL ORBITAL BY EMITTING Orbitals do not have colors, but transitions between orbitals do Formation of the Sun - - - - - Interstellar medium - - Dark patches - - Molecular Clouds - - - - - - - Dust in Molecular Clouds - - - - - - Molecular clouds - - - Three ways in which molecular clouds are unique 1. 2. 3. HOW DID THE SUN FORM? A molecular cloud collapse - - - - - - A Molecular cloud Fragments - - - Multiple Star Systems - - A molecular Cloud Collapses - - - - - - - - - LEARNING GOALS\ Where do stars form? - Why do stars form? - What slows the contraction of a star-forming cloud - Protostars and their properties - - - Hot stars form from cold gas - Protostellar jets are enormous, collimated beams of matter ejected from very young stars called protostars. Collimated simply means that the matter is ejected in parallel (column-like) streams, which in turn means that the jets do not spread out much but extend out very far in relatively straight lines. Emission Nebulae - - - From Protostar to Star - - - - Hydrostatic Equilibrium - - - Most stars exist in pairs - - The big picture Four main components of a galaxy 1. 2. 3. 4. Learning Goals What is the role of rotation in star birth ? - How does nuclear fusion begin in a newborn star? - The formation and age of the solar system Terrestrial Planets - - - - - Rocky planets are all close to the sun Jovian Planets - - - - - Gaseous/icy planets are far from the sun Planets all orbit in the same direction - prograde The planets all orbit the sun in the same direction The Sun and most of the planets rotate in the same direction Most of the massive moons of the planets orbit their planets in this same direction **pro·​grade ˈprō-ˌgrād. : having or being a direction of rotation or revolution that is counterclockwise as viewed from the north pole of the sky or a planet.**