The Planets Exam 1 Study Guide

The Planets Exam 1 Study Guide From the lecture slides you should know the following: Unit 1: Solar System Origins 1. What the Milky Way looks like in the night sky. Like a dippy egg 2. How much of the solar system’s mass resides in the Sun. 99.86% 3. How much of the mass of the planets in our solar system resides in Jupiter. 70% 4. Which are the terrestrial planets. Mercury, Mars, Earth Venus 5. Why our Moon creates a perfect eclipse of the Sun. The sun and moon are at JUST the right size and distance to get a perfect eclipse. The moon is moving away from the Earth at 4cm/yr. 6 & 7. What an astronomical unit (AU) is and the general distance of the planets from the Sun in these units. The order in distance from the Sun of the objects in our Solar System. AU= the distance from the sun to the Earth Mercury .39au Venus .72au Earth 1au Mars 1.5au Asteroid Belt 2-3.5au Jupiter 5au Saturn 10au Uranus 19au Neptune 30au Pluto 30-50au Oort Cloud 63,400au 8. \>>>>> 9. Where the first helium atoms originated. Big bang created all hydrogen atoms then fused into helium atoms 10. The difference in characteristics between hydrogen ions (H+) and molecular hydrogen (H2). H+ have no electron. They are very hot and emit light. H2 is two hydrogen atoms, each with an electron. They are cool and do not emit light. 11. What remains the only way to fuse helium and create heat and light in the modern universe? By doing so in the center of the star 12. The elements that can be fused (created) in the core of a low-mass star like our Sun. Helium, carbon, beryllium, oxygen 13. What happens when helium gets used up in the core of a low-mass star. Begins to slowly collapse 14. The two forces that maintain a force balance within a normally operating star. Pressure out (Fusion) and Gravity in 15. What happens to the temperature of the core of the collapsing star and what is the effect on the outer regions of that star. Core contracts and heats up. The extra heat causes the outer regions of the star to greatly expand and cool and become red. 16. What red giants become red. The cooler temperatures cause the star’s light to shift to the redder part of the spectrum. Red giants have lower core pressure due to no fusion (helium is used up) 1 17. The fate of our Sun. After all helium and hydrogen are used up, our sun will first be a red giant, then The core will eventually shrink and become a WHITE DWARF. The outer regions will violently expand outward. 18. What planetary nebula are. Small cloud of H+ atoms. Can NOT produce planet. Include low mass elements like carbon and hydrogen Mass loss stage of star cycle 19. The fate of the largest stars. Cores condense into a blackhole and the outer regions explode as a supernova Big star > red supergiant > supernova > blackhole/neutron star (4-8 times more massive than our sun) Larger the star, the shorter the lifespan 20. The relative lifespan of stars as a function of mass. As mass increases, lifespan decreases Stars with larger mass take more energy to keep going 21. The heaviest element that can be fused (created) in the core of a high-mass star. Iron 22. What causes a supernova. Balance becomes unstable, and the core condenses so fast that it creates a shockwave 23. What supernovas can create that fusion in the cores of stars cannot. Silicon, sulfur, calcium, and other elements heavier than iron 24. The different processes that can cause a supernova to occur. Can occur when a white dwarf accretes material from a companion star. When two neutron stars collide 25. Where low mass stars acquire their heaviest elements. Inherited from previous supernovas 26. Where the atoms in your body originated. Remnants of stars and hydrogen from the big bang 27. The correct sequence of the stages of the Solar Nebula Hypothesis. Diffused Cloud > Dense Cloud > Accretion Disk > Solar System > Mass Loss 28. The primary source of most current nebula. 29. Where stars are born. Nebulas 30. The type of nebula that are comprised of hot hydrogen ions (H+) and glow. Emission Nebulas are supernova remnants that are very hot (H+) and emit light Molecular Nebluas can birth stars and are cool (H2) 31. What causes nebula clumps to contract into high density regions. Gravity 32. What happens to the force of gravity when objects get closer. Gravity Increases 33. What a solar nebula is. Accretion Disk. A spinning disc of gas and dust, where planets are formed. Spins fast due to conserve of angular momentum 34. The principle of the conservation of angular momentum L=MRw and its main consequence. A spinning object contract, but the state of rotation must get greater Dense regions spin faster as they contract due to the principle 35. What causes spinning nebula clumps to collapse into flat accretion discs. The collisions between gas and dust molecules that serves to cancel up and down motions relative to the spin axis. Collision of objects perpendicular to the plane of rotation. Solar Nebula Hypothesis Unit 2: Planet Formation 36. What chondrules are. Form due to coagulation when little bits and particles rub against each other and combine. Present in large numbers in stony meteorites Building blocks of solar systems 2 37. Where most meteorites are most easily found and where most originate from. Glaciers, because they easily stand out. Sometimes farmers find them in their fields. Most come from asteroids. Some come from the moon and from Mars Originate from fragments of asteroids 38. The differences between chondritic and achondritic meteorites. Chondrites – contain chondrules, unaltered, never went through differentiation Achondrites – no chondrules, altered, internal heating, melted and changed as a result Differentiated, iron, stony, stony-iron 39. What it means for a celestial body to be differentiated. Collisions caused heat and there was radioactive decay. Heavy elements sink and lighter elements rise. Density of materials separated into distinct layers due to the pull of gravity on materials within a body Process of melting and stratification of layers by density within a body 40. Why the interiors of large asteroids and planets are initially very hot inside. Extreme pressure on the outside of the asteroid/planet (from the mass of the object) force the core to heat up (due to compression) which causes it to melt and fuse 41. How an asteroid or planet obtains an iron core. Iron is heavier and sinks down to core 42. The approximate size of a celestial body for it to have experienced differentiation. Any celestial body greater than 30km in diameter 43. The types of meteorites that come from undifferentiated asteroids. 44. How the metallic asteroid Psyche may have formed. It was part of the core of a larger body that was smashed up by a collision 45. The proper order of accretion. A first process is the sticking of microscopic dust into larger grains and pebbles (accreted due to electrostatic attractions as opposed to gravity. A second process is the formation of an intermediate class of objects called planetesimals. A third accretion process has to lead from planetesimals to planets. 46. Where the Lafayette meteorite was found and where it originated. The Laffayette meteorite was found in a drawer of the biology department in 1929 and was from Mars. 47. How the Egyptians were able to make iron tools 2000 years before the iron age. They found iron from meteorites 48. Which terrestrial bodies do not have iron cores. Only some icy bodies. For the most part, differentiated terrestrial bodies have iron cores. 49. The theories of why Mercury has an overly large core. A giant impact blew off the mantle The outer layers were vaporized by a hot young son Mercury was assembled from mostly metal-rich building blocks and never had a large mantle 50. The material available in the outer solar system that allowed the giant planets to grow big. ICE! 51. How was the chemistry of the Sun is determined. We looked at an absorption spectrum and looked at the location of absorption lines to find elements. It shows us the relative abundances of elements. (Black spots) Hydrogen 93.6%, He 6.3%, Other 0.1% (Oxygen, Carbon, Neon, Nitrogen, Magnesium…)\ 52. Know the three most abundant elements in the original Solar Nebula. Hydrogen Helium, Oxygen 53.The basic difference between volatiles and refractory elements/compounds. 3 Volatile: boil at really low temperatures (Oxygen, Carbon, Neon, and Nitrogen). Form ices when far from the sun Refractories: Very high melting temperatures. Condense into metals or rocks closer to the sun 54. Where the iceline is located. Located just inside Jupiter’s orbit 55. How temperature, density, and material available to build planets varies as a function of distance from the Sun in the solar nebula. Density and temperature decrease with distance from sun Mass available to produce planets increases from sun because large orbitals sweep up more 56. The relative size of the cores of the giant planets compared to Earth. Jupter’s Core: 12-45 Cores in Earth Masses Saturn’s Core: 9-22 Cores in Earth Masses Uranus: 0.55 Neptune 1.2 57. Why the gas giants had to form within 3-10 My from the birth of the Sun. They had to form quickly in order to capture hydrogen and helium because the solar wind clears the solar nebula of hydrogen and helium gas. 58. Why Uranus and Neptune did not grow as big as Jupiter and Saturn. The cores of Uranus and Neptune did not grow big enough/fast enough to attract a large amount of hydrogen and helium 59. Whether there is actually cold, solid ice within the ice giants. The mantles of Uranus and Neptune are hot slushy mixtures, but still referred to as icy. Planetary scientists refer to volatiles as ices. 60. The likely composition of the asteroids and comets based on their location relative to the ice line. Mostly rock and metal 61. About how long it took for the Solar Nebula to transform into the Solar System we see today. A few hundred million years Unit 3: Planetary Motions 62. How the angular velocity of a rotating solar nebula varies with distance from the star. L=mrw If a rotating body contracts, it spins faster Fastest close to star and slowest far away 63. How the conservation of angular momentum influenced the spin of the planets. Dictates that the smaller radius leads to faster rotations They obtain the angular momentum of the material they accreted, and thus they spin Spin faster when closer to sun 64. Why the spin axis of most planets is tilted relative to the ecliptic plane. Because of violent collisions with large objects (Uranus got hit so hard that it flipped, and venus spins slowly in the wrong direction 65. Why giant planets have shorter days than terrestrial planets. They spin faster due to being more massive 66. What is at the center of Aristotle’s universe. Earth was at the center 67. How Ptolemy explained the retrograde motion (started going backwards then forwards again) of Mars. 4 Ptolemy came up with “Epicycles”, where mars would move in circles while moving in orbit around earth 68. What Copernicus’ great contribution to science was. Sun at the center 69. The major breakthrough that allowed Kepler to explain the orbits of celestial bodies better than previous models. Elliptical Orbits Kepler’s Laws Eccentricity: 0 (circle) – 0.99 (most elliptic) 1. The Law of Orbits: All planets move in elliptical orbits, with the sun at one focus. 2. The Law of Areas: A line that connects a planet to the sun sweeps out equal areas in equal times. 3. The Law of Periods: The square of the period of any planet is proportional to the cube of the semimajor axis of its orbit. 70. The basic properties of elliptical orbits and what different values of eccentricity means. E= eccentricity: 0<=e<1 E=0 is circular E=.99 highly elliptical 71. Why Mercury’s orbit is more eccentric than the other terrestrial planets. Because it is small and thus more easily perturbed by the gravity of other planets On average, Mercury is closer to Earth 72. Why Pluto has such a highly eccentric orbit. Pluto’s orbit is in an orbital resonance with the much larger Neptune, meaning that these planets interact gravitationally 73. How Neptune was discovered. Neptune was discovered due to Uranus’s “unexplainable” orbital 74. What Keppler’s second law implies about the speed of a planet when its orbit approaches the Sun. Planets move faster when they get closer to the sun. 75. Which parameters influences the time it takes a planet to orbit the Sun. A planet's orbital speed changes, depending on how far it is from the Sun. The closer a planet is to the Sun, the stronger the Sun's gravitational pull on it, and the faster the planet moves. The farther it is from the Sun, the weaker the Sun's gravitational pull, and the slower it moves in its orbit. 76. Which celestial bodies follow Kepler’s laws. All bodies in the universe 77. What happens if you launch a rocket with very little angular velocity. The greater the angular velocity, the greater the centrifugal force The rocket would crash a bit downrange If we launched a rocket into space and stepped out, you would fall to earth and crash 78. What happens if you launch a rocket with a tremendous amount of angular velocity. It will have a higher orbit. If it’s too much, it would leave the orbit Escape velocity – how fast an object has to move to escape gravitational pull 79. What a parabolic orbit represents. Eccentricity = 1 80. The relative angular velocity of Earth’s satellites (natural and otherwise) based on their orbital distance. 5 81. Which orbital parameters of a moon that can be used to determine the mass of a planet. Gravity pull vs size/density of moon from moon’s orbit 82. How the calculation of the mass of a planet based on the orbital characteristics of one of its moons explains Kepler’s 3rd Law. Fgravity = Fcentrifugal (GMm)/r^2 = w^2rm Moon’s mass does not matter M=(r^3 w^2)/G 83. What a hot Jupiter is. Gas giants orbiting close to their stars. They probably formed beyond the iceline and migrated inwards 84. What orbital resonance is. Degree of pull in/out from the eccentricity of orbit due to gravitational effect from other planets/bodies Cause for finding Neptune, based on pull from Uranus Instabilities theorized to cause grand tack changes 85. The motion of Jupiter and Saturn during the Grand Tack. Grand Tack predicts that Jupiter and Saturn formed beyond the iceline, then moved toward the sun, then further away to their present positions Back and forth over the asteroid belt 86. Possible consequences of the Grand Tack. The grand tack caused a lot of objects to be thrown out of the solar system, possibly even some planets. Smaller mars Smaller amount of material left in asteroid belt The grand Tack can explain…  Why the asteroid belt has very little mass (4% of the moon’s mass)  Why Mars did not grow into a much bigger planet despite a larger orbit than the other terrestrial planets  Why Uranus and Neptune have such distant orbits 6