Popular in Course
verified elite notetaker
Popular in Department
This 13 page One Day of Notes was uploaded by Shelby Steichen on Sunday September 14, 2014. The One Day of Notes belongs to a course at a university taught by a professor in Fall. Since its upload, it has received 89 views.
Reviews for AstronomyStudyGuide.pdf
These are great! I definitely recommend anyone to follow this notetaker
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: 09/14/14
Astronomy Study Guide How old is the Universe and how do we know this The universe is about 137 billion years old We know this because we can t see anything further in space than the beginning of the universe Does light travel with an infinite or finite speed and how can we use the answer to observe the Universe at it looked in the past Light moves at a fixed speed Because of this we are able to see the universe as it was when it was younger because the light being produced by the object then is just now reaching us If two objects have a certain relative size you should be able to calculate their relative volumes V1V2 V 43T39R3 will be given radius of one object in comparison to other In what ways are we moving through the cosmos Earth rotates on axis Earth orbits Sun Sun orbits galaxy center What are the names of the different moon phases and how does the moon look during these phases New moon waxing crescent first quarter waxing gibbous full moon waning gibbous third quarter waning crescent Waxing getting bigger Waning getting smaller Gets bigger from right What causes the phases of the moon Phases of the moon are caused by the amount of the illuminated side of the moon we can see from Earth which is caused by the moon s orbit around the Earth What are the relative positions of the earth sun and moon during different phases The Sun and Earth are always the same distance apart and during different times of the moon s orbit the moon can be anywhere around the sun What is the time it takes the moon to go through a complete cycle of phases The moon s full orbit takes about 273 days How much of the moon s total surface is illuminated during each phase How much of the illuminated part can we see Half of the moon s surface is always illuminated by the sun The amount that we can see depends on the moon s location in its orbit How did the Greeks explain the motions of the planets Some ancient Greeks believed that the Sun and other planets orbited the Earth other believed that the Earth and other planets orbited the sun Many also believed that all orbits were in perfect circles because everything in the heavens had to be perfect What is retrograde motion Retrograde motion is when an object in space appears to move backwards in its orbit Did the Greeks believe that the retrograde motion came from real or apparent motions of the plants The Greeks believed this came from a real motion What did Copernicus do to change our understanding of the Universe Copernicus created a model in which the Sun was in the center of our solar system What role did Tycho Brahe and Johannes Kepler play in explaining how planets moved Did this support or refute Copernicus s theory They refuted Copernicus s theory by suggesting that while the planets may orbit the sun the Sun was not at the center of our solar system Rather the planets orbit the Sun in an elliptical What are Keper s three laws 1 Planets orbit the Sun in ellipses with the Sun at one focus o Major axis long side half semi major axis a o Minor axis short side half semi minor axis b o Eccentricity e 1 ba 2 A line drawn from a planet to the sun sweeps out equal areas in equal times gt faster when closer to sunslower when further 3 The orbital period of a planet depends on its distance from the sun P2 a3 p time of orbit in years a semi major axis What were some of Galileo s discoveries that helped to prove that the earth was not at the center of the Universe and how did these experiments prove it o Objects in motion stay in motion objects at rest stay at rest gt Earth can t be moving or we would fly away o Used telescope to prove circles don t govern universefound imperfections on moon and Sun gt Heavens must be perfect What is the difference between speed velocity and acceleration o Speed how fast object is moving o Velocity how fast and in what direction an object is moving o Acceleration change in velocity What causes an object s velocity to change Force anything used to make object accelerate What are Newton s three laws of Motion and what do they mean Be able to describe how each of these laws might appear in your everyday life o Body remains at restconstant velocity unless acted upon by outside force o Net force sum of all forces mass x acceleration o Whenever one body exerts a force on a second body the second body exerts an equal and opposite force on the first body What is the difference between mass and weight o Mass how much matter gt can t change o Weight measure of force exerted on mass What is momentum and how is it different from velocity Momentum mass x velocity How if at all does the gravitational force between two objects depend on their mass and the distance between them Does it depend on anything else or not Fgrav Gm1m2d2 G Earth s gravitational acceleration What do we mean by the concept of net force Net force is the sum of all forces acting upon an object What is angular momentum Angular momentum mass x velocity x radius Always stays the same unless given to something else What does conservation of energy mean Energy can t appear out of nowhere or disappear into nothing but objects can losegain energy by exchanging with other objects How do the gravitational potential and kinetic energy of an object change as it falls from a height Gravitational potential energy will be converted to kinetic energy What is thermal energy and how is it related to kinetic energy Thermal energy is the collective kinetic energy of individual particles moving randomly within a substance How is thermal energy different from temperature Temperature is the average kinetic energy of particles Is the speed of light constant in a vacuum or does it change with different kinds of light The speed of light is always constant What is the difference between absorption reflection or scattering emission and transmission Absorption light taken up by something Reflection Transmission light goes through Scattering reflection off many particles Emission producing light Be able to explain why the sunset is red and the sky is blue o Sky is blue because scattering is more effective in the blue o The sunset is red because during the sunset the blue is so scattered it never meets our eyes How do electrons move about the nucleus of an atom In a cloud of other electrons in about a circular path What does the electron in an atom do when the atom emits a photon Electron moves from a higher energy level to a lower energy one What does the electron in an atom do when the atom absorbs a photon Electron moves from a lower energy level to a higher energy level What are the three types of astronomical spectra and under what conditions are they formed o Continuous spectrum hot light source broad range of wavelengths with no interruptions o Emission hot dense cloud of gas rainbow lines on black background o Absorption hot light source behind a cool dense cloud black lines on rainbow background How does the spacing between energy levels change as you move farther away from the nucleus As you move further away from the nucleus the energy levels increase and the spacing of the levels decreases How does the wavelength of the peak energy output of a blackbody spectral curve depend on the temperature of the blackbody The peak of the curve shows the temperature of the blackbody curve and the temperature gt amax 29 x 1039 T How does the color of an object depend on its temperature ROYGBV gt red cooler blue hotter How does an object s luminosity depend on its temperature and surface area L5671O 8 x A x T4 gt biggerhotter objects are brighter than coolersmaller objects What is the doppler effect Doppler effect The change in the wavelength of light due to the relative motion of the source and the observer along the line of sight How does the magnitude of the doppler effect depend on the direction of the speed in comparison to the line of sight eg parallel perpendicular or at an angle to the line of sight Objects move further away gt redder Objects get closer gt bluer Motion perpendicular to line of sight gt no doppler shift At angle gt doppler shift but not as much Why do we require new energy to be made in the sun all the time for it to be stable If the Sun did not constantly make new energy the Sun would cool and shrink Eventually allowing gravity to consume it What is meant when it is said that the sun is in gravitational equilibrium The pressure created from fusion inside the Sun s core always equals out the force gravity exerts on the Sun What are the main elements that the sun is made of The Sun is mainly made out of hydrogen and helium What is the difference between fission and fusion and which of these powers the sun Fission is splitting up atoms fusion is combining them Fusion goes on in the Sun Where in the sun does fusion occur Fusion occurs in the Sun s core What are the different regions of the sun Outside to inside solar wind corona chromospheres photosphere convection zone radiation zone core Which parts of the sun s structure can we directly see Photosphere How did fusion in the sun start The proto sun formed from a giant gas cloud As it contracted it heated up until the particles were moving so fast that they could undergo fusion What happens next to the size pressure temperature and fusion rate in the core if one of them changes o Temperature decreases gt fusion decreases gas pressure decreases core contractsheats up o Temperature rises gt fusion increases gas pressure increases core expandsheats up What are they ways that I mentioned that astronomers use to determine what s in the interior of the sun and roughly how do these techniques work Making mathematical models observing solar neutrinos observing solar vibrations What are the greenhouse effect global warming and ozone depletion what are the physical processes behind them and how are they different o Greenhouse effect atmosphere traps infrared light reflected off the Earth from the sun which warms the Earth o Global warming the notion that high concentration of CO2 increases global temperature o Ozone depletion areas in the atmosphere where holes have been produced in the ozone layer What is the energy source that powers most every star Nuclear fusion What are the observable properties of stars Luminosity Temperature Radius Chemical Composition Mass What is the difference between apparent brightness and absolute brightness or luminosity as it s sometimes called o Apparent brightness how bright a star appears from Earth o Absolute brightness how bright an object actually is How does the apparent brightness depend on the absolute brightness and the distance Absolute brightness luminosity4139rd2 What is parallax Parallax is an angle used to measure the distance of stars Parallax arcseconds2 How is it measured Observe object at two different points How does the parallax change for stars of different distance Shorter distance larger parallax What is a parsec and how is it defined Parsec unit of distance gt parcsec 1parallax What is the relation between a star s color and its temperature Bluer hotter red cooler What are two ways to measure a stars temperature that we talked about in this and the last class What is the order of the spectral sequence that Cecilia Payne Gaposhkin invented OBAFGKM gt temperature How can astronomers infer the radius of a star R luminosityC4TrT4 What are the characteristics of the three different types of binary stars o Visual binaries able to visually see their distance and how long it takes for them to go around each other o Eclipsing binaries can t see two component stars because they are too close o Spectroscopic binaries How does the light curve of an eclipsing binary depend on the orbital properties of the stars and their respective masses temperatures and sizes If one star in the binary is smaller than the other the total light of the binary will become fainter when the smaller star is blocked from view by the smaller star What is the HertzsprungRussell HR diagram Diagram in astronomy that compares luminosity to temperaturespectral type What spectral class is the sun G Aside from spectral class or temperature what else is needed to figure out a star s place on the HR diagram Mass What are the differences between refracting and reflecting telescopes o Refracting telescope uses transparent glass lenses to focus on light o Earlier telescopes o Reflecting telescope uses curved primary mirror to gather light gt mirror reflects gathered light to secondary mirror gt secondary mirror reflects light to focus at place where it can be observed o Most telescopes today What are the advantages of putting a telescope into space Less atmospheric interference and light pollution Where are different types of stars eg giants super giants main sequence stars white dwarfs in the HR diagram Main sequence stars are found along the main sequence line giants and super giants are found in the upper left corner and white dwarfs are found in the lower left corner What kind of fusion process are stars undergoing when on the main sequence When on the main sequence stars are undergoing hydrogen to helium fusion in their cores How do the luminosity color size and stellar mass and lifetime depend on each other for stars on the main sequence Stars that are less massive tend to be smaller less blue and less luminous However their lifetime on the main sequence is longer than more massive stars More massive stars tend to be more luminous and more blue but their lifetime is shonen How can some giant and supergiant stars be both cool and very luminous They are very massive Why do more massive main sequence stars live shorter lives Because they are more massive they need to use more energy to counteract gravity Because of this they run out of hydrogen in their cores faster How can you determine the age of a cluster of stars The most massive stars on the main sequence define the main sequence turnoff and give the age of the cluster Why do some molecular clouds start to collapse In places where clouds are densercooler gravity will cause the cloud to collapse At what wavelengths to molecular clouds emit the most radiation and why Infrared they are not hot enough to emit in the visible What is the difference between a star and a protostar Protostar the beginning of a star it is part of the collapsing cloud that has heated up and begun to accrete mass and glow What is the cause for a lower limit to the stellar mass Stellar limit 08Msun Anything with a mass lower than this will never get hot enough to start fusion and will become a brown dwarf How are brown dwarfs and stars different Brown dwarfs are not hot enough to use fusion so they supported by another force How is internal pressure provided for brown dwarf stars and how is it different to the pressure in normal stars Brown dwarfs are supported by degeneracy pressure Degeneracy pressure is pressure created by particles that are very close to each other in dense situations Degeneracy pressure also does not depend on temperature What are the phases that a lowmass star goes through in its lifetime Cloud of gas gt protostar gt main sequence gt red giant gt horizontal branch star gt planetary nebula gt white dwarf How do these changes correspond to changes in the structure of the star s interior what nuclear fusion is going on inside the star and the size and temperature of the outside of the star o Main sequence fusion of hydrogen to helium in core o Red giant fusion of hydrogen in shell gt core heats up and shell expands o Increase in luminositydecrease in temperature o Horizontal branch fusion of helium to carbon in core o White dwarf exposed core of star supported by degeneracy pressure What will happen to a white dwarf as it gets old Stays same size gt gets faintercooler What are the general phases in the life of a highmass star and how do the color luminosity and temperature depend on these phases Gas cloud gt protostar gt main sequence gt redblue giant gt supernova gt neutron starblack hole What does a massive star do when its core becomes made of Iron and why When the core becomes made of iron fusion stops in the core and the star is unable to keep producing energy Why are massive stars necessary for the creation of all the elements heavier than hydrogen and helium They are hot enough to create these elements in their core Why does the collapsing core rebound when it gets to be the size of about 10 km Neutron degeneracy pressure comes into play and brings gravity s pressure to halt What can happen in a binary star system that can cause a white dwarf to become a supernova The white dwarf can begin to accrete some gas and other material from the other star When the white dwarf reaches 14 solar masses the core ignites and explodes in a white dwarf supernova What are the differences in the cause and result of a white dwarf supernova and a massive star supernova Massive star supernova leaves behind white dwarf caused by iron in core White dwarf supernova leaves nothing behind caused by accreting mass in a binary with another star What determines if a massive star supernova leaves a black hole or a neutron star Massive star supernova will leave behind a neutron star the iron core left behind is less than 3 solar masses Massive star supernova will leave behind a black hole if the iron core left behind is more than 3 solar masses How do we use variable stars to measure distances to stars o Measure the period of a variable star its pulses o Determine its luminosity o D luminosity4Trab What is the size of the Milky Way and how does this compare very roughly to the distances of nearby stars and nebula 100000 light years What is our galaxy made of Stars gas dust How are gas stars and dust distributed in our galaxy Gasdust distributed in thin disk Stars distributed in thicker disk with bulge On what kinds of orbits to stars and gas move in the parts of galaxies where they exist Gas and disk stars move in roughly circular orbits Bulge and halo stars move in elliptical with random orientation Where does most star formation in the galaxy happen Spiral arms What are the different parts of our galaxy and how are they different in the kinds of stars that are in them the motions of those stars the amount of gas and dust the abundance of heavy elements in the stars 0 Disk o Stars ranging in ages o Roughly circular orbits o Large amounts of heaver elements o Bulge and halo o Old stars o Randomly oriented orbits o Low amounts of heavier elements What is the evidence for the presence of dark matter in our galaxy and what are the properties of dark matter Dark matter o Invisible o Everywhere o Only know about it because of its gravitational pull What evidence leads us to believe that there is a supermassive black hole that is lying at the center of our galaxy o Very small object in center of galaxy radiates highly in radio o Nothing visible in infraredoptical o Stars orbit it in ellipses What are the different types of galaxies Spirals Ellipticals lrregulars How do these types differ in eg their shapes the ages of the stars in them the amount of gas and dust the amount of star formation how the stars move in them Spirals o Blue star forming disks o Low to moderate mass o Dominated by rotation Ellipticals o Old stars o Moderate to high mass o Dominated by random motions lrregulars o Super star forming amorphous shape o Low mass o Dusty What is the big bang Theory that the universe expanded from a tiny speck in a huge explosion What is the cosmic microwave background radiation and what kind of spectrum does it have Cosmic Microwave Background radiation left over from the Big Bang Continuous spectrum
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'