F L O R I
D A S T A T E
U N I V E R S I T
Review Materials Test #2
What is listed here is not expected to be an exhaustive summary, but simply lists many of the high points that you should know for the test; You should also use review questions and problems, self tests, and other materials at the ends of each chapter in the text, as well as quizzes and any assigned homework problems, to assist you in your study.
Anything discussed in the text or lectures is valid material to be included in the tests.
Each test will be multiple choice, consisting of ~25-30 problems, of which ~6-8 will be numerical. Useful information such as equations and numerical constants will be given to you on the test sheets;
You may use a standard scientific or business calculator (make sure it has new batteries), and must bring a #2 pencil and your university ID with you to the test.
Practice tests (old tests from previous semesters of Dr. Lind's AST section, that deal with the same material, and with the test given in the same style as the upcoming test (with their accompanying answer keys), are handed out only to students that come to the test review sessions. It is recommended that this test be used as a true "practice test", and that you look at the answer key only after trying the problems, and then study more carefully the material you missed.
The summary outlines of the lectures (but not the practice tests) will be posted at this site a few days to a week before each test to help you in your study.
|"Learning From Other Worlds"
the Formation and Properties of the Solar System
-- 99% of the mass of the solar system is in the Sun.
-- the sizes of the objects in the solar system are comparable to a tennis-ball-sized Sun and grains of sand and "bb"s strewn across an area far larger that a football field.
-- Pluto's orbit tipped 17.2°, but all the others are nearly coplanar (meaning that visually they all take nearly the same path around the sky - through the zodiac and near the ecliptic plane).
-- exceptions (Venus, Uranus, Pluto rotation axes) explained by catastrophic events.
-- revolutions of most satellites are in the same (counterclockwise) direction and in nearly the same plane. Exceptions (retrograde orbits) like Saturn's Pheobe are probably all captured moons.
-- exceptions are only for "missing planet" at the radius of the asteroids and imperfect agreement for the position of Pluto, which is thought to be an ejected moon.
-- ~75% hydrogen ~25% helium ~2% heavier elements
-- this is nearly identical to the composition ratios of the Sun itself.
-- Moon rocks, meteorites, Sun's evolutionary age, etc.
Any description of the origin of the solar system (or any other planetary system) must be able to explain the origin of these properties, both similarities and differences.
-- all stars form because of the gravitational contraction of the denser parts of very large clouds of gas and dust.
-- as the star is being born (contracting and heating as a protostar, prior to the turn-on of nuclear fusion), it remains surrounded by the cocoon of gas and dust.
-- rotation of the cloud flattens much of the material into a spinning disk around the protostar's equator.
-- planets form from this rotating disk of gas and dust around the young star.
* then accretion into larger clumps called planetesimals. (this is the same as is found in asteroids, meteorites, and cometary material)
* the largest clumps attract the most additional material (because they have the strongest gravity), sweeping up the smaller chunks, and more gas and dust to form protoplanets and finally the planets.
-- as the nuclear fusion of the star turns on, the gas and dust cocoon is blown away by the increasing stellar wind.
This is a very general process!! It should be common to the formation of all stars.
* Using Doppler and other techniques, many planets have been found orbiting other stars, including complex planetary systems with up to four planets (these searches find large planets in small orbits near the star most easily.)
-- Condensation and accretion: the process that brought the brought the matter of the planet together into one place also left the early planetary surface scarred with craters.
-- Differentiation: internal heat caused the molten interior of the planet and separation of the dense material to the core and lighter, less dense material to the surface.
-- Volcanism and flooding: the hot interior of the planet and the cooler solid crust floating on top is breached by volcanoes and the shifts of plate tectonics. This process left the low-lying areas of the surfaces covered with nearly flat basaltic sheets of lava (mare, or maria(plural)), and on Earth with a covering of water (the oceans).
-- Weathering, surface erosion, and sedimentation: these processes remake the planetary surfaces by the interactions of the planetary lithosphere (atmosphere, crust, and upper mantle.)
-- Freezing of the planetary interior: Planetary interiors cool at different rates, with large planets cooling the slowest and tiny worlds cooling rapidly.
The same process is seen throughout the
solar system; the only difference is the condensation temperature and distance
from the Sun
The Earth as a Planet:
- need to know the shape and size of the Earth,
nearly spherical (oblate spheroid), 6400km (4000miles) in radius
The Moon: Our Nearest Neighbor
The Geometry of the Sky: Earth,Moon,and Sun
thegeometrical relationship between Earth, Moon, and Sun leads to:
Lessons from Comparative Planetology
* absorbs UV radiation - protects against skin cancer and mutations; Mars has none.
* increasingly denser atmosphere could trap more heat.
* CO2 levels strongly affected by mankind's burning of fossil fuels.
* worlds with liquid water oceans absorb CO2, and reduce the greenhouse effect (difference between Venus and Earth.) [NOTE: that there are actually opposing actions here from water, because gaseous water in the atmosphere as clouds or vapor act as greenhouse gases just like CO2, and increase atmospheric heating.]
* a large amount of water found in rocky meteorites.
* Paradox that life needs oxygen, but that the best way to increase oxygen is life.
* contains most of the complex hydrocarbons of life, but no water.
-- satellites (moons):
* Generally the moons closest to the planet orbit in or near the planet's equatorial plane in nearly circular orbits, and were probably formed when the planet was formed. The moons farthest from the planet are often smaller, in tilted, retrograde, or elliptical orbits, and can be captured satellites with composition similar to comet nuclei.
* the small terrestrial worlds have few or no moons.
* Earth and Pluto, with moons nearly as large as the planet, are oddballs.
* seen for all four gas giants.
* due to tidal forces very near massive bodies - "Roche limit" caused when the tidal forces from the planet are stronger than the tensile strength of rocks - tearing apart any moon that strays too close to the planet.
density = mass/volume
* history of terrestrial planets: cratering, differentiation, volcanism/flooding, weathering/rebuilding of the surface
* the same process is seen throughout the solar system; the only difference is the condensation sequence and distance from the Sun (which leads to different composition for different worlds).
* some planets and satellites seem to have stopped and frozen part way through the process, or have cooled all the way to inertness.
Venus and Mars.
* Only on four worlds have we seen active (currently erupting) volcanoes: Earth (rock); Io (sulfur), Triton (liquid nitrogen geysers), and Europa (waterspouts; only identified after a late reanalysis of Voyager data).
* molten iron or iron alloys in terrestrial interiors (best example is Earth).
* liquid metallic hydrogen in gas giant interiors (best example is Jupiter).
* the largest planets have a strong enough gravitational attraction that when they were forming they swept out a huge volume of space - large enough to create tiny planetary systems of their own.
-- Use Kepler's Third Law, a separation of the planet to its's moon and the moon's orbital period find the planet's mass (remebering that the moons mass is much s than the planet).
P2(yrs) = A3(AU) /(m1+m2)(multiples of the Sun's mass)
P2(sec) = 4p2 x A3(meters)/G x (m1+m2)(kilograms)
where G = 6.67x10-11m3/kg.sec2
Tidal forces: the differential forces when large objects pull on each other, cause planetary distortion, internal churning, heating and even the tearing apartt of the rocks that make up the world, leading to:
-- tidal locking: Earth's
Moon, Mercury, Pluto/Charon; one side always faces the larger body (Mercury
odd 2:3 orbit/rotation locking)
-- Both Neptune and Pluto were mathematically predicted before discovery because of the gravitational influence they had that influenced and perturbed the orbits of the other outer planets.
-- the same is true of the detection of extrasolar planets (they cause a wobble of their parent star's position, which is detectable using the Doppler effect).
-- only object visited by manned missions; maria, highlands, cratering, origin, locked rotation from tidal drag; eclipses; tides.
-- heavy cratering, scarps; densest planet, odd (locked) rotation; why no atmosphere; finished evolutionary sequence.
-- dense atmosphere (carbon dioxide, sulfuric acid clouds, very strong greenhouse effect); impact cratering; clear evidence of significant volcanic activity sometime in its history; Magellan radar mapping, Venera landers (Russia).
-- small, thin atmosphere (escape velocity of gas molecules near their average kinetic energy); seasons (variations in polar caps, water trapped in permafrost, dry ice); evidence of large dormant volcanoes; evidence of past thick atmosphere and liquid surface water; visit of Viking lander (70's), Mars pathfinder ('97), Mars Global Surveyor (present); Life?
-- more mass than all other planets combined; Great Red Spot; thin ring; Shoemaker-Levy 9 comet impacts; huge (strong) magnetosphere; liquid metallic hydrogen.
-- huge complex ring system of dust and boulders; average density less than water (0.7gm/cm3)
-- tipped over (very odd seasons); evidence of many cometary impacts.
-- discovered by amateur astronomer William Herschel with his homemade backyard telescope.
-- Great Dark Spot; 1000mph winds; very cold;
-- first planet discovered because of a mathematical prediction - tested the orbit of Uranus, and found a discrepancy which had to be caused by the presence of another massive object out there.
-- never visited by space probes yet; its density, size (diameter), atmosphere, and surface albiedo (brightness or darkness) variations found by mutual eclipses with its moon Charon and occultations of stars; eccentric, highly tipped (17°) orbit;
-- discover in 1930 by Clyde Tombaugh in response to orbital variation in Uranus' orbit unexplained by the presence of Neptune; later found that Pluto's masscould not account for that variation either; it was far too small!! There must be some other massive object(s) out there!!
know the names and some of the distinguishing properties of each of the four Galilean moons of Jupiter: Io, Europa, Ganymede, and Callisto; and of the distinguishing properties of the following moons of the other outer planets: Titan and Mimas (Saturn), Miranda (Uranus), and Triton (Neptune).Meteorites, comets and asteroids:
know the definitions of meteoroid, meteor, and meteorite.
* some of the rocky asteroids have some carbon compounds - carbonaceous chondrites.
-- very elongated elliptical orbits.
-- A meteor is the streak of light caused when a meteoroid (an piece of rock or metal or ice) streaks through the Earth's atmosphere. A particularly bright meteor is called a bolide.
-- Any material that survives the fiery passage through the atmosphere is a meteorite.
* each meteor is visible for a fraction of a second to several seconds, based on its size and brightness.
* ~5-10/hr fall into the atmosphere that are bright enough to see from any one point on Earth's surface, with that number almost doubling between the hours of midnight and dawn (that being the 'ram' direction of Earth's orbital motion).
* all meteors in a single shower appear to come from a single point in the sky (the radiant), which is the direction toward the comet's orbit.
* kinetic energy of orbiting objects:
This page last updated on April
1,2004 by David M. Lind
© 2004 Department of Physics, Florida State University. All rights reserved.