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Flashcards in Lectures 7-12 Deck (110)
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What does the part of the Solary Sytem occupied by planets look like?

flattened, everything in almost the same plane


What is the shape of orbits of dwarf planets?

very elliptical


What is the shape of the orbit of the 8 major planets?

nearly circular, all orbit in same direction and nearly on the same plane


Name the planets in order.

Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune,


Properties of the Sun

-over 99.9% of solar system's mass
-mostly H and He gas (plasma)


Properties of Mercury

-made of metal and rock
-large iron core
-desolate, cratered, cliffs
-very hot and very cold 425C day -170C night


Properties of Venus

-almost the same size as Earth
-surface hidden by clouds
-extreme greenhouse effect
-even hotter than Mercury 470C day and night


Properties of Mars

-looks like Earth
-polar caps, canyonns...


Properties of Jupiter

-much farther from Sun than the inner planets
-mostly H/He
-no solid surface
-300x the mass of Earth
-many moons, rings
-Galilean moons= Io,Europa,Ganymede,Calisto


Properties of Saturn

-giant, gaseous like Jupiter
-rings= not solid made of small chunks of ice and rock each orbiting like a small moon
-many moons (incl. Titan)


Properties of Uranus

-smaller than Jupiter and Saturn, still much larger than Earth
-H/He gas and hydrogen compounds (H2O,NH3,CH4)
-extreme axis tilt
-moons and rings


Properties of Neptune

-similar to Uranus but not the axis tilt


Properties of Pluto and other dwarf planets

-much smaller than major planets, icy-comet like composition
-pluto has a moon Charon= almost the same size as Pluto


Properties of terrestrial planets

-smaller size and mass
-higher average density
-made mostly of rocks and metals
-solid surface
-few if any moons and no rings
-closer to the Sun and together with warmer surfaces


Properties of jovian planets

-larger size and mass
-lower average density
-made mostly of H He and hydrogen compounds
-no solid surface
-rings and many moons
-farther from the Sun and from each other with cooler temperature cloud tops


How do you measure the distance to Venus?

Measure apparent position of Venus on Sun from two locations on Earth.
-use trigonometry to determine Venus' distance from the distance between the two locations on Earth
-that's how we measured the AU


What is a transit of a planet?

When planet passes between the Earth and the Sun and you can see it on the Sun.


What is a flyby mission?

-fly by a planet just once, captured by gravity and sling shot further
Voyager 1 (1977)125 AU away -at the edge of the solar system 19 billion km
Voyager 2 (1977) 101 AU, 15 billion km away


Describe the nebular theory

-Solar system formed from the gravitational collapse of a giant interstellar gas cloud


What are the exceptions to the usual pattern in the Solar System?

-Uranus' tilted axis
-Earth's large moon
-Venus' rotation


What is meant by galactic recycling?

Elements that formed planets were made in stars and then recycled through interstellar space


What caused the orderly patterns of motion in our solar system?

Conservation of angular momentum.-increasing speed of rotation with contraction
Flattening-collisions between particles in the cloud


Why are there two major types of planets?

- as cloud contracting it heats up, inner part hotter than outer, rock can be solid at higher temp than ice


What is the frost line?

A line inside which too hot for hydrogen compounds to form ices,
outside= cold enough to form ices


How did the terrestrial planets form?

-small particles of rock and metal inside the frost line
-planetesimals built up as the particles collided
-gravity eventually assembled these into terrestrial planets= accretion


Explain accretion of planetesimals.

Gravity draws them together, many small ones collected into bigger objects, eventually planets.


How did the jovian planets form?

-ice formed small particles outside the frost line
-larger planetesimals and planets able to form
-gravity of rock and ice in jovian planets draws in H and He gases, so that's why they're bigger-gas doesn't take as much gravity.
-each jovian planet is like a miniature solar system


What is the composition of the Solar system?

98% H and He gas don't condense in the nebula
1.4% hydrogen compounds (H2O, methaneCH4,ammonia NH3) -condense at 150K
0.4% rock-various mineral-condense at 500-1300K
0.2% Metal-iron,nickel,aluminum condense at 1000-1600K


How come there isn't any H He gas floating around anymore?

Combination of photons and solar wind blew them away.


How did Sun's rotation change over time with regard to the nebular theory?

-the young Sun rotated much faster than now
-friction between solar magnetic field and solar wind probably slowed it down.