ch.6 – Space – Flashcards

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The solar system exhibits?
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clear patterns of composition and motion. These patternsare far more important and interestingthan numbers, names, and other trivia.
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Large bodies in the Solar System have?
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Orderly Motions.
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All planets have nearly?
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Circular orbits going the same direction in nearly the same plane.
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Most large moons orbit their planets in what direction?
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The same direction, which is also the direction of the sun's rotation.
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What two categories do planets fall into?
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Small, Rocky terrestrial planets and large, hydrogen-rich jovian planets.
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What distinct regions are asteroids and comets located in swarms in the solar system.
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Asteroid Belt(metal & Rock), Oort Cloud, and Kuiper belt(Rich in ice).
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Planets are very tiny compared to?
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The distances between them.
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The Sun.
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Is 99.9% of solar systems mass, 100x bigger than earth. Made of Mostly H/He gas (plasma) converts 4million tons of mass into energy each second.
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Mercury
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•Made of metal and rock; large iron core •Desolate, cratered; long, tall, steep cliffs, no moon •Very hot and very cold: 425°C (day), -170°C (night)
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Venus
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•Nearly identical in size to Earth; surface hidden by clouds •Hellish conditions due to an extreme greenhouse effect •Even hotter than Mercury: 470°C, day and night •No moon
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Earth
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•An oasis of life •The only surface liquid water in the solar system •A surprisingly large moon
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Mars
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•Looks almost Earth-like, but don't go without a spacesuit! •Giant volcanoes, a huge canyon, polar caps, and more •Water flowed in the distant past; could there have been life? 2 moons, but perhaps captured small asteroids
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Jupiter
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•Much farther from Sun than inner planets •Mostly H/He; no solid surface •300 times more massive than Earth •4 Galilean moons, rings Active Volcanoes
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Ganymede
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Largest moon in Solar System.
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Callisto
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A large, cratered "ice ball"
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What are the names of the 4 Galilean Moons?
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lo Europa Ganymede Callisto
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Saturn
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•Giant and gaseous like Jupiter •Spectacular rings •Many moons, including cloudy Titan •Cassini spacecraft currently studying itInsert
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T/F Rings are solid; they are made of countless small chunks of ice and rock, each orbiting like a tiny moon.
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F Rings are NOT solid; they are made of countless small chunks of ice and rock, each orbiting like a tiny moon.
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Uranus
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•Smaller than Jupiter/Saturn; much larger than Earth •Made of H/He gas and hydrogen compounds(H2O, NH3, CH4) •Extreme axis tilt •Moons and rings
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Neptune
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•Similar to Uranus (except for axis tilt) •Many moons (including Triton)
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All four jovian planets have?
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ring systems.
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Other planets have ring particles that are
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smaller and darker than Saturn's.
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Pluto and Other Dwarf Planets
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•Much smaller than other planets •Icy, comet-like composition •Pluto's moon Charon is similar in size to Pluto
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Other Icy Bodies (NOT Jovian planets)
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•There are many icy objects like Pluto on elliptical, inclined orbits beyond Neptune (Kuiper belt objects). •The largest ones are comparable in size to Earth's Moon (Eris is bigger than Pluto).
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Motion of Large Bodies
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•All large bodies in the solar system orbit in the same direction and in nearly the same plane. •Most also rotate in that direction.
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Two Major Planet Types
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•Terrestrial planets are rocky, relatively small, and close to the Sun. •Jovian planets are gaseous, larger, and farther from the Sun.
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Swarms of Smaller Bodies
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•Many rocky asteroidsand icy comets (random orientation)populate the solar system.
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What theory best explains the features of our solar system?
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According to the nebular theory,our solar system formed from a giant cloud of interstellar gas. (nebula= cloud)
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Notable exceptions:
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Rotation of Uranus, Earth's large moon, and so forth
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Where did the solar system come from?
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Galactic Recycling •Elements that formed planets were made in stars and then recycled through interstellar space.
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T/F We can NOT see stars forming in other interstellar gas clouds, lending support to the nebular theory.
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F We CAN see stars forming in other interstellar gas clouds, lending support to the nebular theory.
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Where do stars form?
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Stars form in dark clouds of dusty gas in interstellar space.
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What is the gas called between stars?
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interstellar medium.
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The rotation speed of the cloud from which our solar system formed...
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must have increased as the cloud contracted.
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Rotation of a contracting cloud speeds up for what reason?
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the same reason a skater speeds up as he/she pulls in his/her arms.
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Collisions between particles in the cloud caused what?
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it to flatten into a disk.
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Collisions between gas particles in a cloud gradually reduce what?
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random motions.
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Collisions between gas particles also reduce what motions?
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up and down motions.
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The spinning cloud flattens as it?
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shrinks.
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Observations of disks around other stars support what hypothesis?
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the nebular hypothesis.
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As gravity causes the cloud to contract, it?
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heats up.
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Inner parts of the disk are?
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hotter than outer parts.
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Rock can be solid at much higher temperatures than
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ice.
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Inside the frost line:
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Too hot for hydrogen compounds to form ices Outside
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Outside the frost line
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Cold enough for ices to condense
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Formation of Terrestrial Planets
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•Small particles of rock and metal were present inside the frost line. •Planetesimals of rock and metal built up as these particles collided. •Gravity eventually assembled these planetesimals into terrestrial planets.
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Tiny solid particles stick to form what?
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planetesimals.
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Gravity draws planetesimals together to form what?
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Planets.
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accretion
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process of assembly of a planet.
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Many smaller objects collected into
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into just a few large ones. From planetesimals to planets.
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Formation of Jovian Planets
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•Ice could also form small particles outsidethe frost line. •Larger planetesimals and planets were able to form. •The gravity of these larger planets was able to draw in surrounding H and He gases.
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The gravity of rock and ice in jovian planets draws in what?
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H and He gases.
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Moons of jovian planets form in?
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miniature disks.
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Where did Asteroids and Comets come from?
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They are leftover planetesimals, according to the nebular theory.
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When did leftover planetesimals bombarded other objects
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in the late stages of solar system formation.
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Water may have come to Earth by way of?
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icy planetesimals from the outer solar system.
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The unusual moons of some planets may?
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be captured planetesimals.
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Giant impacts
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might also explain the different rotation axes of some planets.
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ages of the rocks
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We can determine the age of a rock through careful analysis of the proportions of various atoms and isotopes within it.
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Some isotopes decay into
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other nuclei.
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half-life
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is the time for half the nuclei in a substance to decay.
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Dating the Solar System
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Age dating of meteorites accreted tells us that the solar system is about 4.6 billion years old.
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the oldest moon rocks are?
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4.4 billion years old.
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The oldest meteorites are?
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4.55 billion years old.
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Planets probably formed?
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4.5 billion years ago.
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How do we detect planets around other stars?
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•Direct:Pictures or spectra of the planets themselves •Indirect:Measurements of stellar properties revealing the effects of orbiting planets
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The Sun therefore wobbles around that center of mass
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with the same period as Jupiter.
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Measuring a star's Doppler shift can tell us its?
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motion toward and away from us.
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We can detect planets by?
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measuring the change in a star's position in the sky.
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tiny motions
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are very difficult to measure
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Short period means
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small orbital distance
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First extrasolar planetto be discovered
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1995
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The planet around 51 Pegasi has a mass similar to Jupiter's, despite its
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small orbital distance.
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transit
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when a planet crosses in front of a star (edge-on).
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The resulting eclipse reduces the star's apparent brightness and tells us the
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planet's radius.
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When there is no orbital tilt, an accurate measurement of
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planet mass can be obtained.
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Measurable Properties
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•Orbital period, distance, and shape •Planet mass, size, and density •Composition
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Most of the detected planets have
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orbits smaller than Jupiter's.
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Planets at greater distances are harder to detect with the
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Doppler technique.
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Most of the detected planets have
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greater mass than Jupiter.
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Planets with smaller masses are harder to detect with the
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Doppler technique.
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More than one in ten stars examined so far have turned out to have
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Planets
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The others may still have smaller (Earth-sized) planets that cannot be detected
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using current techniques.
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How do extrasolar planets compare with those in our solar system?
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—Detected planets are all much more massive than Earth. —Most have orbital distances smaller than Jupiter's, and have highly elliptical orbits. —―Hot Jupiters‖ have been found so far.
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Do we need to modify our theory of solar system formation?
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Migration and encountersmay play a larger role than previously thought.
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