Popular in Astronomy 1001
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ASTR Notes Chapter 1 Solar System the sun the planets and all the other objects orbiting the sun Milky Way Galaxy our diskshaped collection of stars Galaxy a great island of stars in space containing between a few hundred million and a trillion stars Local Group our galaxy is in a group with other galaxies Galaxy Clusters groups of galaxies with more than a few dozen members Super Clusters regions in with galaxies and galaxy clusters are most tightly packed Universe the sum total of all matter and energy Astronomical Unit AU Earth s average distance from the sun which is 150 million kilometers Light year ly the distance that light can travel in 1 year 10 trillion kilometers unit of distance 1 lightyear speed of light x1 year Observable Universe the portion of the entire universe that we can potentially observe Big Bang the point at which the expansion began 14 billion years ago the entire universe is expanding but individual galaxies and galaxy clusters do not expand because of gravity Nuclear Fusion the process in which lightweight atomic nuclei smash together and stick or fuse to make heavier nuclei how stars are formed Earth rotation spin orbit revolution it rotates counterclockwise so does the sun Ecliptic plane Earth s orbital path that defines a at plane Axis Tilt earth is tilted 235 degrees from a line perpendicular to the ecliptic plane the axis points are almost directly pointed at a star called Polaris or the North Star Dark Matter pulls things together Dark Energy spread things apart expansion Chapter 2 39PP P Constellation a region of the sky with welldefined borders 88 official constellations Northern Hemisphere are from ancient Middle East and Southern Hemisphere is from 17th century European explorers Celestial Sphere the imaginary sphere on which objects in the sky appear to reside when observed from Earth North Celestial sphere South Celestial sphere Celestial Equator Ecliptic the path the sun follows Local Sky the sky seen from wherever you happen to be standing dome like can only see half of the sphere at all times Horizon boundary between Earth and sky Zenith point directly overhead Meridian imaginary half circle stretching from the horizon due south through the zenith to the horizon due north Direction azimuth along horizon Altitude above horizon Angular size the angle it appears to span in your field of view moon and sun 12 degree Angular Distance is the angle that appears to separate a pair of objects in the sky 60 Arcminutes degree 60 Acrseconds 1 arcminute Circumpolar stars near the north celestial pole they remain perpetually above the horizon circling counterclockwise Latitude affects the constellations we see because it affects the locations of the horizon and the zenith relative to the celestial sphere The altitude of the celestial pole in your sky is equal to your latitude Zodiac the constellations along the ecliptic 13 official constellations Seasons caused by Earth s tilt toward Polaris throughout the year making the orientation of the axis relative to the Sun change over the course of each orbit Northern Hemisphere is tipped toward the Sun in June and away from the Sun in December no tilt no seasons 1 Summer solstice June Northern Hemisphere is tipped most directly toward the Sun and has the most direct sunlight 2 Winter solstice December Northern Hemisphere receives the least direct sunlight 3 Spring equinox March 4 Fall equinox September Earth s axis tilt 235 degrees Precession a gradual wobble that alters the orientation of Earth s axis in space it is caused by gravity s effect on a tilted object the spinning rotating Earth precesses because of gravitational tugs from the Sun and the moon the wobble does not change the tilt degree but it does change where the sun falls on a constellation over time Moon Lunar phases 295 days the Moon s appearance in our sky changes as its position relative to the Sun changes Full moon rises around sunset a firstquarter moon must rise around noon New moon moon is between the sun and the earth Full to New Waxing New to Full Waning Before or after New moon crescent Before or after Full moon gibbous Synchronous rotation the moon rotates on its axis in the same amount of time it takes to orbit Earth we only ever see one side Earthshine sunlight re ected by Earth faintly illuminates the dark side of the moon 399 PE39 3993P Lunar Eclipse Earth lies directly between the sun and the moon so earths shadow falls on the moon Can see everywhere moon must be Full Umbra shadow earth makes and blocks the sunlight completely from the moon Penumbra shadow the earth makes and only partially blocks the sunlight Total Lunar Eclipse moon is totally in umbra Partial Lunar Eclipse part of moon is in umbra most common Penumbral Lunar Eclipse moon is only in penumbra Solar Eclipse Moon lies directly between the sun and the earth so the moons shadow falls on Earth only see in certain places Total Solar Eclipse in moons umbra Corona appears Annular Eclipse moons umbra does not reach earth Partial Solar Eclipse in moons penumbra Totality when the moon is entirely engulfed in the umbra BOTH occur equally often Nodes the two points in the moon s orbit where it crosses the ecliptic plane new or full moons must occur when crossing through Eclipse Seasons two periods each year when the nodes of the moon s orbit are nearly aligned with the Sun Saros Cycle the combination of the changing dates of the eclipse seasons and the cycle of lunar phases makes eclipses recur in cycle of about 18 years cannot predict time or place of occurrence Planetary Motion Apparent Retrograde Motion planets usually move eastward through the constellations but they occasionally reverse course moving westward through the zodiac Stellar ParallaX the apparent shift in the position of a nearby star that occurs as we view the star from different positions in Earth s orbit if the sun each year Chapter 3 0 Modern clock from Egypt 4000 years ago with star clocks 1500 BC hourglass 0 Solar Calendar a calendar that us synchronized with the seasons so that seasonal events such as the solstices and equinoxes occur on approximately the same dates each year 0 Lunar Calendar synchronize with the Moon s 295 day cycle of phases 12 months only 354 or 355 days 11 days shorter than Solar Calendar lunar phases repeat on the same dates about every 19 years Metonic Cycle 0 Archaeoastronomy archaeology and astronomy a study of past cultures measure of time 0 Scientific Model a conceptual representation created to explain and predict observed phenomena 0 Geocentric Model of the cosmos placed a spherical Earth at the center of the universe Greek Astronomers Anaximander invented the idea of the celestial sphere Pythagoras Earth as a sphere oating at the center of the celestial sphere that is geometrically perfect Plato Heavenly objects move in perfect circles at constant speeds that reside on huge spheres encircling Earth Aristotle all the spheres responsible for celestial motion were transparent an interconnected like the gears of a giant machine Ptolemy adapt and synthesize earlier ideas into a single system that agreed with observations at the time Ptolemaic Model to explain the apparent retrograde motion of the planets each planet moved around Earth on a small circle that turned upon a larger circle A planet following this circleuponcircle motion would trace a loop as seen from Earth with a backward portion of the loop mimicking apparent retrograde motion geocentric Copernicus Copernican Revolution origin of modern science used Aristarchus s Sun centered solar system for an explanation for apparent retrograde motion heavenly motion is still perfect Tycho best nakedeye observations ever made planets must orbit the sun but earth is stationary because of his inability to detect stellar parallax Kepler Ellipse planetary orbits are not circles but instead are a special type of oval Semimajor axis half of the axis of an ellipse long axis Major axis Eccentricity a quantity that described how much an ellipse is stretched out compared to a perfect circle measurement of how elongated an ellipse is Kepler s Laws of Planetary Motion The orbit of each planet around the Sun is an ellipse with the Sun at one focus a planets distance from the sun varies during its orbit it is closest at the point called perihelion and farthest at the point aphelion the average of a planets perihelion and aphelion distances is the length of its semimajor axis Aphelion farthest from the sun Perihelion closest to the sun As a planet moves around its orbit it sweeps out equal areas in equal times the planet travels faster when it is nearer to the Sun and slower when it is farther from the Sun More distant planet orbit the Sun at slower average speeds obeying a precise mathematical relationship p2a3 p is the planets orbital period and a is its average distance from the Sun in AU we can use this law to calculate a planets average orbital speed he thought this was due to magnetism but Newton shows its gravity Galileo Proved the Greeks Wrong through 3 Basic Objections Aristotle said that the Earth could not be moving otherwise all objects would be left behind as the Earth moved along Galileo used rolling balls to demonstrate that a moving object remains in motion unless a force acts to stop it Newton s first law of motion Aristotle said that the heavens sun moon planets and stars must be perfect and unchanging Galileo used Tycho s supernova and comet observations to prove that the heavens could change he also built a telescope in 1609 to prove that the sun had imperfect spots and the moon had mountains and valleys that were imperfect No one had detected stellar parallax that should occur if Earth orbits the Sun Galileo did not prove this fact but he did offer evidence by showing the Milky Way he argued that the stars were far more numerous and more distant than Tycho had believed Galileo also observed four moons that orbited Jupiter not Earth thus getting rid of a Earthcentered model Nature of Science Ancestors knowledge of science good science Scientific method hypothesis simple prediction results do again Hypothesis a tentative explanation or an educated guess simple prediction from hypothesis Hallmarks of Science Scientific Process begins with someone going out and looking at nature in a general way rather that doing sets of experiments Scientific Model must make testable predictions about natural phenomena Modern science seeks explanations for observed phenomena that rely solely on natural causes Science progresses through the creation and testing of models of nature that explain the observations as simply as possible Pseudoscience false science check all three hallmarks of science Paradigm general patterns of thought Theory when a powerful yet simple model makes predictions that survive repeated and varied testing Scientific theory can never be proved true beyond all doubt because future observations may disagree with its predictions Astrology the apparent positions of the sun moon and planets among the stars in our sky in uence human events Kepler and Galileo s discovery of a Sun centered solar system broke the bond between astronomy and astrology Chapter 4 Motion 1 Speed how far something will go in a certain amount of time 60 miles per hour 2 Velocity the speed and the direction of an object 60 miles per hour going due north turning means a change in direction causing the velocity to decrease 3 Acceleration if the velocity of the object changes in any way slowing represents a negative acceleration turning is a form of acceleration You do not feel effects when moving at constant velocity airplane Types of Acceleration 1 Acceleration of gravity the acceleration of a falling object g 98ms2 gravity accelerates all objects at the same amount regardless of their mass air resistance causes the difference in acceleration 2 Momentum mass X velocity Only way to change momentum of an object is to apply force to it Net force overall force action on an object represents the combined effect of all the individual forces put together A change in momentum occurs only when the net force is not zero Changing an objects momentum means changing its velocity as long as its mass remains constant Net force causes acceleration Angular momentum Any object that is either spinning or moving along a curved path Earths rotation rotational angular momentum Earths orbit orbital angular momentum Torque the type of force that can change an objects angular momentum Mass amount of matter in your body same anywhere Weight the force that a scale measures when you stand on it depends on mass and the forces acting on you changes because of changes of force Freefall falling without any resistance to slow you down you are in freefall whenever there s nothing to prevent you from falling Weightless freefall makes you weightless no forces Astronauts are in a constant state of freefall Newton s 3 Laws of motion laws that govern the motion of everything 1 1st Law an object moves at constant velocity if there is no net force action upon it Objects at rest velocity0 2 2rld Law what ha ens to an ob39ect when a net force is resent PP J P Force mass X acceleration Fma Force rate of change in momentum Explains why larger planets have greater effect on asteroids and comets than small planets The ball is accelerating even if it has a steady speed because it is constantly changing direction and therefore has a changing velocity 0 The string is pulling the ball with an inward force ball has an inward acceleration as it moves around the circle 3 3rd Law for any force there is always paired with an equal and opposite reaction force 0 Objects always attract each other through gravity 0 Conservation laws Laws of Conservation 1 Conservation of Momentum as long as there are no external forces the total momentum of interacting objects cannot change that is their total momentum is conserved 0 Total combined momentum of the two balls remains the same both before and after the collision 0 No external forces are accelerating the balls 0 The amount of forward momentum the rocket gains is equal to the amount of backward momentum in the gas that shoots out the back 0 The total momentum of you and Earth remains the same at all times 2 Conservation of Angular Momentum as long as there is no external torque the total angular momentum of a set of interacting objects cannot change 0 Angular momentum m x v x r mEarths mass v its orbital velocity r the radius of the orbit its distance from the sun 0 Earth will continue to orbit the sun unless something comes along to take angular momentum away 0 Earth s orbital speed must be faster when it is nearer to the Sun and slower when it is farther away from the sun 0 Explains why we see spinning disks in the universe 3 Conservation of Energy energy cannot appear out of nowhere or disappear into nothingness 0 Objects can gain or lose energy only by exchanging energy with other objects 0 All actions involve exchanges of energy or the conversion of energy from one from to another 0 Energy is what makes matter move Types of Energy 1 Kinetic energy energy of motion 0 The kinetic energy of a moving object is l2mv2 mobjects mass vobjects velocity 0 Falling rocks molecules moving in the air 2 Radiative energy energy carried by light 0 All light carries energy 0 Light can cause changes in matter 3 Potential Energy stored energy 0 It might be converted into kinetic or radiative energy 0 Gravitational potential energy a rock on a ledge Standard Unit of Energy joule Thermal Energy represents the collective kinetic energy of the many individual particles moving randomly within a substance like a rock or the air or the gas within a distant star 0 Still objects still have energy of random motions contain substantial energy 0 Thermal energy measures the total kinetic energy of all the randomly moving particles in a substance 0 Temperature measures the average kinetic energy of the particles 0 Temperature is measured in Kelvin no negatives scales starts at absolute zero 0 Thermal energy depends on temperature and density of substance 0 Astronauts lose their body heat by emitting thermal radiation because there is extremely low density in space Gravitational Potential Energy depends on mass of object and how far it can fall as a result of gravity 0 An object has more gravitational potential energy when it is higher and less when it is lower 0 Object near Earth s surface gravitational potential energy is mgh mmass gacceleration of gravity hheight above the ground MassEnergy the amount of potential energy contained in mass 0 Emc2 E amount of potential energy mmass of object c speed of light 0 A small amount of mass contains a huge amount of energy 0 Energy can be transformed into mas Universal Law of Gravitation 0 Every mass attracts every other mass through the force called gravity 0 The strength of the gravitational force attracting any two objects is directly proportional to the product of their masses 0 Gravitational force follows an inverse square law 0 Inverse square law FGmlm2d2 F force of gravitational attraction M1M2 masses of the two objects d distance between their centers G a constant called gravitational constant G 667 X lOAll mA3kg X s2 Newton Extends Kepler s Laws 1 Planets are not the only objects with elliptical orbits 2 Ellipses are not the only possible orbital paths 0 Bound orbits orbits in which an object goes around another object over and over again 0 Unbound orbits paths that bring an object close to another object just once 3 Objects orbit their common center of mass 0 Center of mass the point at which the two objects would balance if they were somehow connected Two objects attracted by gravity actually both orbit around their common center of mass 4 Orbital characteristics tell us the masses of distant objects Tides Newton s version of Kepler s third law the relationship between orbital period and average distance depends on the masses of the orbiting objects The orbital period of a small object orbiting a much more massive object depends only on its orbital distance not its mass Orbital energy the sum of the planets kinetic and gravitational potential energies stays the same orbits cannot change spontaneously Gravitational encounter one way that two objects can exchange orbital energy in which they pass near enough so that each can feel the effects of the others gravity Friction can cause objects to lose orbital energy Escape velocity depends on whether you start from the surface or from someplace high above the surface because gravity weakens with distance it takes less energy hence less velocity to escape a point high above Earth than from Earth s surface Tides rise and fall twice a day Tidal force difference in attraction that stretches the entire Earth to create two tidal bulges one facing the moon and one opposite the moon Tides affect both land and ocean The sun also exerts a tidal force on the Earth causing the Earth to stretch along the sunearth line Gravitational force between the Earth and the Sun is much greater than the Earth and the moon but there is a much greater distance to the Sun than to the moon Suns pull is relatively small Spring Tides new moon and full moon the tidal forces of the Sun and the moon work together Neap Tides firstquarter moons and thirdquarter moons tidal forces of the Sun and the moon counteract each other Tidal Friction the process of tidal forces on the Earth created friction The moons gravity pulls back on the bulges slowing earths rotation The gravity of the bulges pulls the moon slightly ahead of its orbit causing the moon to move farther from the earth Moons growing orbit gains the angular momentum and energy that the earth loses as it rotation slows Synchronous Rotation the moon always shows the same face to the earth It is a consequence of tidal friction Tidal forces gives the moon 2 tidal bulges along the earthmoon line Once the moons rotation slowed to the point at which the moon and its bulges rotates at the same rate there was no further source for tidal friction The gradual slowing of the earth rotation will eventually make earth keep the same face to the moon as well Objects fall at the same rate Galileo s discovery that the acceleration of a falling object is independent of its mass Einstein described new insights of gravity in his general theory of relativity Chapter 5 Radiative Energy energy that light carries Greater warmth greater molecular motion Energy measurement Joules Power rate of energy ow Measure power in Watts Spectrum rainbow of light White light contains all the colors of the rainbow Black light no color Primary Colors of Vision red green blue Diffraction grating a piece of plastic or glass etched with many closely spaced lines how to produce a spectrum Light can interact with Matter in 4 ways 1 2 3 4 Emission a light bulb emits visible light Absorption your hand absorbs light Transmission matter that allows light to pass through it Re ectionscattering light bounces off matter in the same direction light bounces off matter in a random manner Transmit light are said to be transparent Absorb light are called opaque Wavelength the distance from one peak to the next or one trough to the next Frequency the number of peaks passing by any point each second Cycles per second Hertz Hz frequency measurement Speed of the waves tells us how fast their peaks travel across the pond Wavelength x Frequency Speed Electromagnetic Wave Field used to describe the strength of force that a particle would experience at any point in space Electromagnetic Wav light waves are traveling vibrations of both electric and magnetic fields The distance between the peaks in this row of electrons would tell us the wavelength of the light wave while the number of times each electron bobbed up and down would tell us the frequency Speed of light all light travels the same speed 300000 Kilometers per second Longer the wavelength the lower the frequency red and vice versa Short wavelength high frequency blue Photons light has properties of both particles and waves Electromagnetic spectrum the complete spectrum of light including Phases Radio waves longest wavelength light carry very little energy Microwaves Infrared light lies beyond the red end of the rainbow Visible light Ultraviolet light blue light carry harmful energy X rays shorter wavelengths Gamma rays shortest wavelengths Electromagnetic Radiation another name of all types of light from radio waves to gamma waves Atoms what all ordinary matter is composed of Protons positive in nucleus has weight Neutrons no charge in nucleus has weight Elections negative out of nucleus no weight Atomic Number each different chemical element contains a different number of protons in its nucleus Atomic Mass Number the combined number of protons and neutrons in an atom Isotopes versions of an element with different numbers of neutrons of Matter Chemical bond the interactions between elections that hold atoms in a molecule together Solid ice liquidwater gaswater vapor Pressure andor temperature can cause phase change Sublimation process by which molecules escape from a solid Evaporation process by which molecules escape from a liquid Molecular dissociation at high temperatures the collisions become so violent that they can break the chemical bonds holding individual molecules together molecules spilt into pieces Ions charged atoms Ionization process of stripping electrons from atoms Plasma hot gas in which atoms have become ionized Atom absorbs light the electron moves up Atom emits light the election moves down Pressure the force per unit pushing on an objects surface Energy in Atoms 1 They possess massenergy in the amount mc2 by virtue of their mass 2 They possess kinetic energy by virtue of their motion 3 They contain electrical potential energy that depends on the arrangement of their electrons around their nuclei Energy levels only a few particular energies are possible possible energies known 1eV 160 X 10Al9 Energy level transitions an electron can rise from a low energy level to a higher one or fall this can only occur when an electron gains or loses the specific amount of energy separating the two levels Spectra Spectroscopy the process of obtaining a spectrum and reading the information it contains Intensity the amount of light at each wavelength 3 types of spectra 1 Continuous light bulb rainbow 2 Emission Line Spectrum a thin or lowdensity cloud of gas consists of bright emission lines against a black background 3 Absorption Line Spectrum cloud of gas lies between a light bulb and us shows dark absorption lines over the background rainbow A molecules can absorb or emit a photon when it changes its rate or vibration or rotation Molecular Bonds molecules produce spectra with many sets of tightly bunched lines found in infrared portion Thermal Radiation the temperature dependence of light Thermal Radiation Spectrum spectrum to measure temperature of light measured in Kelvin Law 1 each square meter of a hotter object s surface emits more light at all wave lengths Law 2 Hotter objects emit photons with a high average energy shorter wavelength Doppler Effect motion of distant objects relative to us from changes in their spectra Blueshift an object is coming toward us shorter wavelengths and bluer Redshift an object is moving away from us longer wavelengths and redder Rest wavelengths wavelengths in stationary clouds of hydrogen gas Larger the shift the faster they are moving Doppler effect can also reveal information about the motion within the object If the object is rotating the spectra line will appear wide the faster it rotates the larger the line Chapter 6 Eyes 0 Refraction a change in the direction in which light is travelling 0 Parallel rays of light converge to a point Focus or Focal Point 0 Parallel rays of light enter the lens directly through the center are not bent 0 Light rays that enter the lens farther from the center are bent 0 Bending of rays for an image of the original object 0 Focal Plane the place where the image appears in focus of the lens 0 The focal plane is on the retina Camera 0 Detector makes a permanent record of the image 0 Exposure time use shutter control to control the amount of time during which light collects on the detector allowing it to record details that are too faint to be seen with faith exposures 0 Pixels electronic clips that are physically divided into grids of picture elements Telescopes 0 Lightcollecting area tells us how much total light a telescope can collect at one time measure by square diameter 0 Angular resolution the smallest angle over which we can tell that 2 stars are distinct humans have an angular resolution of l arcminute 0 Interference limits a telescopes angular resolution 0 Diffraction limit the angular resolution that a telescope could achieve if it were limited only by the interference of light waves depends only on diameter of the telescopes primary mirror and the wavelength of the light being observed 1 Refracting telescope uses transparent glass lenses to collect and focus light like a eye 2 Re ecting telescope uses a precisely curved primary mirror to gather light this mirror re ects the gathered light to a secondary mirror that lies in front of it 0 Re ecting telescopes are used more today than refracting because glass is too heavy and it is hard to get highquality glass with precisely shaped surfaces What are telescopes used for 1 Imaging 0 Yields photographs of astronomical objects 0 Mainly use invisible light Xrays 2 Spectroscopy 0 Astronomers obtain and study spectra 0 Spectrographs use diffraction gratings to separate the various colors of light into spectra that are recorded with a detector 3 Time monitoring 0 Tracks how an object changes with time 0 Light curves graphs that show how an objects intensity varies with time Groundbased Observations 0 Hard to measure daylight weather scattering of manmade light blurring of images by atmospheric motion most forms of light do not reach the ground 0 Light pollution scattered light is humanmade and obscures our view of the night sky 0 Turbulence distortion of light by the atmosphere winds and air currents makes stars look like they twinkle 0 Adaptive optics technology that eliminates much of the blurring and allow telescopes to achieve angular resolution close to their diffraction limit makes telescope move opposite way of winds to cancel out movement Invisible Light 1 Radio Telescopes 0 Most common type in the world 0 Receiver collects the radio waves re ected by the primary mirror and sends them to the television 0 Very large because radio wavelengths are very large 0 They can work together to get much better angular resolution 2 Infrared Telescopes 0 Do not reach the ground of the Earth 0 Must be put into space 0 Get too hot on Earth and cannot be detected 3 Ultraviolet Telescopes 0 Must be put in space 0 Cannot reach ground 4 XRay Telescopes 0 Must be in space 0 Cannot reach ground 0 They have a lot of energy that can penetrate materials 0 Grazing incidence mirrors X rays graze the tilted surface as the rays de ected toward the focal plane 5 GammaRay Telescopes 0 Cannot look for them they penetrate materials too badly 0 Can look for short bursts Beyond light 0 Neutrino lightweight subatomic particle that is produced by nuclear reactions 0 Cosmic rays highenergy subatomic particles from space 0 Gravitational waves different from the nature of light but travels at the speed of light Interferometry linking two or more telescopes together to achieve the angular resolution of a much larger telescope Chapter 14 0 Gravitational contraction sun generates energy by slowly contracting in size gas moving inward converting gravitational potential energy into thermal energy not possible because only 25 million years allowed Sun is stable with 2 kinds of balance 1 Gravitational equilibrium is between the outward push of internal gas pressure and the inward pull of gravity the energy release by fusion heats the gas and maintains the pressure that keeps the sun in balance against the inward pull of gravity 2 Energy balance rate at which fusion releases energy in the suns core and the rate at which the suns surface radiates this energy into space without it the balance between pressure and gravity would not remain steady 0 Can last 10 billion years Sun Elements 0 Sunspots appear as dark splotches on the Sun s surface 0 Sun does not rotate at the same rate completes one rotation every 25 days and the rotation period increases with latitude to about 30 days near the solar poles 0 Sun luminosity power output is 38 X 10quot26 Watts 0 Solar wind the stream of charged particles continually blown outward in all directions from the sun Sun Structure 0 Corona outermost layer of the atmosphere emits most of the suns X rays 0 Chromosphere middle layer of the solar atmosphere emits most ultraviolet light cooler temp 0 Photosphere visible surface of the sun moves like boiling water sunspots intense magnetic fields density of gas becomes so low that photons can escape into space 0 Convention Zone where energy generated in the solar core travels upward transported by the rising of hot gas and falling cool gas called convention 0 Radiation Zone where energy moved outward primarily in the form of photons of light very hot 0 Solar Core source of suns energy nuclear fusion transforming hydrogen into helium very hot and dense Nuclear fission splitting an atomic nucleus Nuclear Fusion sun makes energy by combining or fusing two or more small nuclei into a larger one ProtonProton Chain 1 2 protons fuse forming a nucleus consisting of 1 proton and 1 neutron which is the isotope of hydrogen known as deuterium the lost of the positive charge is carried off by a positron a neutrino that is a subatomic particle with a very tiny mass is also produced this step must happen twice and requires 4 protons 2 lof the deuterium nuclei collides and fuses with a proton making helium3 2 protons and 1 neutron with 1 gamma ray photon occurs twice 3 Requires the addition of another neutron to the helium3 making helium4 nucleus with 2 protons How the Sun will die With each fusion reaction converts 4 hydrogen nuclei into 1 helium nucleus the total number of independent particles in the solar core will decrease over time the decrease in particles will slowly increase the cores temperature and fusion rate to keep the core pressure high enough to counteract the stronger compression of gravity Radiative Diffusion the very slow journey outward migration of photons each time a photon collides with an electron the photon gets de ected into a new and random direction Learn About Inside the Sun Mathematical Models primary way of learning about the interior of the sun use law of physics to predict internal conditions Solar Vibrations observe vibrations of the suns surface that are similar to the vibrations that earthquakes cause on earth the movements are caused by the movement of gas and pressure look for Doppler shifts Solar Neutrinos observe subatomic particles made by fusion reactions in the core they do not interact with many matter scientists place neutrino detectors deep underground in mines to capture them SunEarth Connection Solar activity sunspots cooler temp occur in pairs solar ares huge explosions Magnetic field lines magnetic fields are invisible Solar Prominences gas in the suns chromosphere and corona becomes trapped in loops Solar Flares send bursts of X rays and charged particles into space most dramatic storm created by changes in magnetic fields Corona Holes some regions of the corona barely show up in X ray images nearly devoid of hot coronal gas Solar wind particles streaming outward from the corona blows through the solar system effects on planets surface atmosphere and magnetospheres provide satellites with sample material from the sun Coronal Mass Ejections ares and other solar storms sometimes eject large numbers of highly energetic charged particles from the suns corona they can create a geomagnetic storm in Earth s magnetosphere which can lead to strong auroras but also hamper electrics and satellites Sunspot Cycle A cycle in which the average number of sunspots on the sun rises and falls Solar maximum sunspots are most numerous form at lower latitudes Solar minimum fewest sunspots form at solar equator Average length of between maximums 11 years The suns entire magnetic field starts to ip turning magnetic north into magnetic south at each maximum Suns complete magnetic cycle 22 years Sun s convention and Sun s rotation is what causes sunspots 0 Suns rotation is faster at its equator than near its poles 0 At the equator the lines circle the sun every 25 days but the poles lag behind Suns total output of energy never changes Fusion decreases core pressure lowers core temperature rises Exam 1 Distance 0 AU for solar system 0 Light year for universe NOT a measure of time Motion of the Earth remember rotation How fast the earth orbits the sun Get numbers Universe is expanding dark energy Celestial sphere Angular Diameter moon 5 degree sun5 degree 0 1 degree 60 arcminutes 0 1 60 arcseconds Constellations Newton s Laws Tides ANY RED TEXT PAY ATTENTION Question 1 What is your cosmic address Earth Solar System Milky Way Galaxy Local Group Local Cluster Universe 2 Scale of the Solar System 1 to 10 billion scale Earth compared to sun 3 Calculate angular size of object 4 Circumpolar stars North celestial pole never rise or set 5 Find latitude based off of North Star in regards to picture 6 Constellations 7 How fast things in the solar system remember slide 8 What is not a motion in the solar system 9 What does it mean to be a light year 10 Angular diameter of mars 11 Why do we have seasons Tilt of the Earth northern hemisphere tilt toward sun north is summer and south is winter 12 If the earth was tilted more extreme 50 degrees Seasons more extreme 13 How long does it take the earth to precess one time 26000 years 14 In 13000 years the Earth will tilt towards Vega June would turn to winter because of the tilt change 15 Vernal Equinox Spring 16 Autominal Equinox Fall 17 Recognize each moon phase 18 Know what times correspond to each moon phase 19 What phase is earth in compared to the earth Opposite phases when looking from the moon to the earth 20 On the sun looking at the earth and the moon Would you see the moon all the time No the moon disappears behind the earth in lunar eclipses on the node 2 times a year 21 On the sun would you see moon phases No it is always full moon seen from the sun 22 How many lunar eclipses do we get a year 2 23 How many solar eclipses do we get a year 2 24 What happens when the moon is farther away would it be able to block the sun Annular Solar Eclipse the sun shows a ring around the moon 25 Is the parallax bigger or smaller when the star is closer The parallax has a bigger shift when the star is closer 26 Which one of the following are not Kepler s laws Know Kepler s laws 27 Which ancient astronomer was the first one to recognize that planets traveled in ellipses Kepler 28 Which astronomer proposed that planets traveled on epicycles Geocentric model Ptolemy 29 Which astronomer was the first one to propose a suncentered model Heliocentric model Copernicus 30 Tycho Copernicus Kelper Galeleo Ptolemy Know most important fact on all of these astronomers 31 Semimajor axis know the law pquot2 aquot3 and how to use 32 Scientific theory Know what it means Collect information develop theory something challenged the theory start over 33 Scientific model 34 Scientific method 35 When in the international space station and throw a wrench and you go backward Newton s 3rd Law 36 Know all of Newton s Laws Know how they are different in each scenario 37 Is it speed velocity or acceleration Know the difference between all three and know the relationship and the definitions 38 Computational Calculate eccentricity Equation No axial tilt on a planet no seasons 39 What are the differences between mass and weight Mass is intrinsic weight is determined by gravitational forces 40 When are we weightless Free fall astronauts are in constant free fall as the shuttle orbits earth 41 The closer the planet is to the star the faster it moves vis versa 42 What is conserved Energy and momentum 43 How can you prove it is conserved Mass X velocity X radius angular momentum always the same no matter where you are in orbit 44 Do the moon and the sun pull on each other equally Yes everything pulls on each thing equally 45 Which one is greater The earths pull on the moon or the moon on the earth Neither they are the same 46 Sun compared to the earth on what direction does the force act on the planet Force is towards the sun 47 Two different objects 212degree water or 400 degree oven which one would the thermal degree be hotter The water it has a higher density and more of them the total thermal energy is greater 48 If I lined up the sun earth and moon in a line would the tides be less or greater compared to them in disarray Greatest high tides would happen when the sun earth and moon are in a line they work together 49 If the moon were more massive or in a different alignment would the tides be more severe Yes 50 Formula At what wavelength would something give light at a certain temperature Given temperature at what wavelength would the object emit most of its light Veins Law Thermal Radiation know how to use equation 51 Why are there absorption lines What causes absorption lines when you look at the sun The gas absorbs the energy 52 Does all light travel at the same speed Yes all forms of light travel at the same speed 53 In which of these scenarios would you have the largest energy level being absorbed The electron will rise up the farther it moves up and leaves the form ionization 54 What are things you can learn from spectra Blue shift moving toward you redshift moving away composition temperature calculate rotational speed 55 What can spectra not do If the object is moving left or right tangential movement 56 Computational know emition lines what is star doing Formula vc 57 Does the wavelength get shorter as you move closer Yes and longer when you move away 58 CCDs peak wavelength calculate it from temperature 59 CCDs what do they do Compare to film Charged coupled device better than photographic film know what they do 60 What is a pixel 61 What is the most important thing of telescopes The bigger the diameter the more light collecting area the better the image 62 Calculation of telescope and light collecting compared to another telescope 63 Can you see X rays from earth No they are absorbed in the atmosphere 64 Know what type of mirror or lens it is off of a picture of rays lab 6 65 What is the reason why you have to color X ray images Many images are colorized to help you see them because they are invisible
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