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Definition
| the hypothesis that the planets formed from the same cloud of gas and dust that formed our sun |
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how long ago did the solar nebula in our solar system condense? also, how old is our solar system? |
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approximately 4.6 billion years ago thus, 4.6 billion years old |
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| how did the solar system form? |
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Definition
slowly rotating solar nebula contracted under gravity, formed a protostar at its center and flattened. dust grains coalesced by gravity, slowly accreting to form protoplanets -- planets |
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how long did it take for our solar system to form? after it formed... what began happening inside of the sun's core? |
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Definition
100 million years after which thermonuclear fusion began in the core of the sun |
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| differences between terrestrial and outer planets |
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Definition
terrestrial planets are small, rocky, dense, close to the sun, have few moons, have no rings, have solid surfaces outer planets are large, gaseous, less dense, far from the sun, separated by large distances, have ring systems and many moons, don't have solid surfaces |
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terrestrial planets how big? rock or gaseous? how dense? proximity to the sun? moons? rings? solid surface? |
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small rocky dense close to the sun few moons no rings solid surfaces |
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outer planets how big? rock or gaseous? how dense? proximity to the sun? moons? rings? solid surface? |
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large gaseous less dense far from the sun separated by large distances ring systems many moons no solid surface |
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small, rocky world. remnants of the creation of the solar system |
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| most asteroids lie between... |
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Definition
| mars and jupiter in the asteroid belt |
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size of asteroids largest asteroid composition of asteroids |
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Definition
smaller than 1 km in diameter largest: Ceres (940 km) made up of rock and metal |
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| relationship between the kirkwood gaps in the asteroid belt and the cassini division in the rings of saturn: |
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Definition
both caused by disruptions in the orbit of small objects by larger planets or moons in both cases, the periods of the small objects are simple fractions of those of the larger disturbing object |
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| the kirkwood gaps are caused by |
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Definition
are caused by the gravitational pull of Jupiter which nudges asteroids into new orbits |
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one of the small, icy bodies that orbit the sun and produce tails of gas and dust when they approach the sun "dirty snowballs" |
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gas and dust water ice and volatile material |
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| comets that enter the inner solar system typically have ____ orbits |
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Definition
| typically have elliptical orbits |
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| the tail of the comet is longest when... |
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Definition
| longest when the comet is closest to the sun |
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differences between asteroids and comets 1. composition 2. physical appearance |
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Definition
1. asteroids are made of rock and metal comets are made of water ice and volatile material ((but old comets lose volatile materials)) 2. comets have tails |
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easily vaporized comets are made of these materials |
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| the collection of icy planetesimals believed to orbit in a region from just beyond Neptune out to 100 AU or more. |
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what is found in the Kuiper belt? how far away from the sun? how is the Kuiper belt distribution shaped? |
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Definition
- hundreds of millions of coments found here -extending to 500 AU from the sun -a donut shaped distribution |
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| origin of the "dirty snowballs" which become comets when they are deflected into orbits that bring them closer to the sun... |
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Definition
| kupier and oort belts surrounding the solar system |
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| the four largest satellites of Jupiter, named after their discoverer, Galileo |
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| a small bit of matter heated by friction to incandescent vapor as it falls into earth's atmosphere |
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| a meteor in space before it enters earth's atmosphere |
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| a meteor that survives its passage through the atmosphere and strikes the ground |
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a small particle of interplanetary dust burning up and glowing as it enters the Earth's atmosphere (meteor) |
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stony meteorite that contains both chondrules and volatiles. these chondrites may be the least-altered remains of the solar nebula still present in the solar system |
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meteor shower
define.. caused by... |
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Definition
a multitude of meteors that appear to come from the same region of the sky believed to be caused by comet debris |
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| a meteor shower (many shooting stars) is related to this astronomical phenomenon..... |
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Definition
| the phenomenon of the passage of earth through the remnants of an old comet |
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| relationship between comets and meteor showers |
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Definition
dust and fragments left behind by an extinct comet spreads out along the entire path of its former orbit when earth passes through this path, you get a meteor shower |
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Definition
| the time required for half of the atoms in a radioactive sample to decay |
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role of gravity and heat in transforming the solar nebula into the solar system -rising temperature pushed out what in inner solar system? -how did it form a new protosun? |
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protostar's rising temperature vaporized icy substances in the inner region pushed light gases (H, He) out leaving inner solar system free of these light elements grav flattened the solar nebula, attracted material to its center, contraction headed gas to form new protosun |
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| the density a planet would have if its gravity did not compress it |
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boundary beyond which water vapor could freeze to form ice |
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| the sequence in which different materials condense from the solar nebula as we move outward from the sun |
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| one of the small bodies that formed from the solar nebula and eventually grew into protoplanets |
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the growth of a particle by addtion of material from surrounding gas, atom by atom |
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the sticking together of solid particles to produce larger particles the coalescence of large bodies by mutual gravitational attraction |
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accretion formed [outer/terrestrial] planets around a star |
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massive objects, destined to become a planet resulting from the coalescense of planetesimals in the solar nebula |
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the process by which a forming body such as a planet gravitational captures gas from its surroundings |
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| the separation of planetary material according to density |
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| the release of gases frmo a planet's interior |
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the possible role of an asteroid collision with earth in the extinction of the dinosaurs and 2/3 species 65 million years ago: |
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Chicxulub crater in the Yucatan Penninsula in Mexico and an iridium-rich layer in the Earth's crust asteroids are rich in iridium- an asteroid 10 km in diameter produced the crater cut off sunlight leading to exinctions |
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| the intense cratering during the first 0.5 bil years in the history of the solar system |
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| NEOs (near earth objects) |
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| a small solar system body (asteroid or comet) with an orbit near enough to the earth that it poses some threat of eventual collision |
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| an explanation of a phenomenon involving slow, steady processes of the sort seen happening in the present day |
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| an explanation of a phenomenon involving special, sudden, perhaps violent events |
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heat released by infalling matter during the formation of the planetary body |
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the hypthetical source of comets a swarm of icy bodies believed to lie in a spherical shell extending to 100,000 AU from the sun |
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a disk of dust found by infrared observations aroudn some stars the dust is debris from collisions among asteroids, comets, and the Kupier belt objects |
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| a planet orbiting a star other than the sun |
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| evidence for extra-solar planets |
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Definition
1. doppler measurements of radial velocities of stars they orbit.... caused by the planet tugging back and forth on teh star to form different directions as the plane orbits teh star 2. measurements of the proper motions of the stars they orbit (also caused by planet's gravitational tug on its star) 3. measurements of the change in brightness caused by planets passing in front of them |
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| extra-solar planets cannot be easily understood because.. |
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| their eccentric orbits cause them to be not easily understood |
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