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47 Cards in this Set
- Front
- Back
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How does planet formation begin (formation of planetesimals)? |
Condensation (gas --> liquid)
** Same as asteroids/meteorites (Condensation --> accretion --> growth --> differentiation for largest bodies) |
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What does the word "planet" stand for in Greek? |
Wanderer |
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What led to the discovery of Ceres and Pallas? |
Thought there was a missing planet between Mars and Jupiter |
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How did the name "asteroid" come about? |
Herschel coined the term -Asteroids resemble moving point-like stars (planets appear as full disks) |
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What led to the discovery of Neptune? |
-Discovered by Galileo (not identified as a planet at first)
-Uranus showed small deviations from its orbit that could not be explained by gravity of the sun/all known planets (predicted position of perturbing body --> found Neptune - only planet not found by accident) |
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What led to the discovery of Pluto? |
Search for Planet X (a plant thought to be perturbing Uranus - but was just a poor estimate of Neptunes mass) - found Pluto |
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What are some properties of Pluto? |
-Almost the same size as Charon (its moon) -Very cold (40K) -Thin N atmosphere (refreezes onto surface) -Pluto and Neptune's orbits cross but they're in a 3:2 orbital resonance (never will hit) - pluto has 17 degree tilt with plane of Neptune |
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Alternative names to asteroid? |
- minor planets -planetoids |
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Why is pluto and the other asteroids now not called planets? |
-Found Eris even farther from Sun and larger (10th planet?) - would be soo many planets if we didn't further define the meaning of planet |
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What defines a planet? |
A celestial body that: 1) orbits the sun 2) sufficient mass for self gravity to make it nearly round/rigid in shape 3) cleared neighborhood around its orbit (pluto failed this criteria)
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What defines a dwarf planet? |
A celestial body that: 1) orbits the sun 2) sufficient mass for self gravity to make it nearly round/rigid in shape 3) NOT cleared neighborhood around it 4) not a satellite |
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What defines everything else (other than planets and dwarf planets)? |
Small Solar System Bodies (includes asteroids and comets) |
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How many planets does our solar system have? |
8! (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune) |
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How many dwarf planets are there so far? What are their names? |
5 - Eris, Pluto, Haumea, Makemake, Ceres |
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Asteroids are... |
-Are rocky with a wide range of sizes, up to hundreds of kms in diameter -do not have atmospheres -most are made of a mix of rocks/metals -some have their own moons -we've landed on an asteroid before (Ceres) |
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Is the asteroid belt densely or loosely packed? |
very loosely (million km between them) |
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How do asteroids and other minor planets get their names? |
16 characters or less -one word prefered -pronouncable -non-offensive -not too similar to existing names -can only name ofter political/military activities 100 years after event |
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Are there more small or large asteroids? |
Many small, only few big (total amount of asteroids decreasing in solar system) |
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If you added up the mass of all the asteroids in the asteroid belt, what object would be closest to this mass? |
The moon - actually only 4% of the moon's mass (asteroids are not massive even when added up) |
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What do asteroids look like? |
-Unrounded -Cratered |
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What is the best way to find the densities of asteroids? |
Find an asteroid with a moon and use Kepler's 3rd law (see the asteroid perturbed by gravity of moon)
-Measure asteroid densities by using mass and size |
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Where are most asteroids found in our solar system? |
In the asteroid belt between Mars and Jupiter |
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Why are there very few asteroids beyond Jupiter's orbit? |
Ice could form in the outer solar system |
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Which explanation for the asteroid belt seems the most plausible? |
The belt is where the most asteroids happened to survive |
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What prevented the planetesimals from accreting into planets between Mar's and Jupiter? |
Jupiter's gravity prevented this. (the asteroid belt is not the remains of a destroyed planet) |
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What are the 3 types of asteroids (S, C, & M-type)? |
S-type: -silicate (rocky, dominate inner region of belt - 17%)
C-type: -carbonaceous (dominate outer region - 75%)
M-type: -metal rich (8%) |
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Define Meteoroid? |
Small to boulder sized particle of debris in solar system |
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Define Meteor? |
Bright trail left by a meteoroid that enters Earth's atmosphere (shooting star) |
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Define Meteorite? |
Portion of meteoroid/asteroid that survives its passage through the atmosphere and impact with the ground |
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Define Meteorology? |
atmospheric science |
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Meteor + Meteorite = |
Composition of body in Solar System (meteor track = orbit of the parent body that originates from the asteroid belt) |
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What are the two types of meteorites? |
1) Primitive - unchanged in composition since they first formed (chondrites) - majority
2) Processed - experienced processes like volcanism or differentiation (achondrites) - geologically younger (subdivide into metal-rich and rock)
* some meteorites are pieces of the Moon and Mars |
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What is the nucleus of a comet commonly referred to as? |
"dirty snowball" |
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What is a coma? |
Atmosphere that comes from heated nucleus of comets |
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What is a plasma tail? |
Gas escaping from the coma of a comet, pushed by solar wind |
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What is a dust tail? |
extension of a comet pushed by photons (comet's tail grows as the comet gets close to the Sun) |
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Why do meteors in a shower appear to emanate from the same area of the sky? |
B/c of Earth's motion through space (meteors appear to converge in a point at a distance) |
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Most meteors originate from _______, and most meteorites originate from ________. |
comets, asteroids (many more comets cross the Earth's orbit, but comet (icy material) does often survive passage through atmosphere (therefore no meteorites) |
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What is the Oort Cloud? |
-Lead to LONG PERIOD COMETS -Surrounds the solar system -comets on random orbits/any direction -spherical distribution -comets formed closer to the Sun (kicked out by gravitational interactions with jovian planets) |
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What is the Kuiper belt? |
**Kuiper belt is right outside Neptune (outer solar system) -Lead to SHORT PERIOD COMETS -in ecliptic plane (flat plane) - aligned with planetary orbital plane/same direction of rotation (KBOs orbit like short period comets) -comets on orderly orbits -comets formed in Kuiper belt
** essentially failed to become planets |
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Do cosmic collisions occur? |
Yes, asteroids/comets can impact with planets (can see evidence of crater chains on moon and mercury) |
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About how often is it estimated that an asteroid or comet impacts the Earth with sufficient energy to cause mass extinction? |
Once every hundred million years |
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What is the hypothesized event that lead to the dinosaur extinction? |
Impact of Chicxulub crater --> lead to major climate change --> extinction of species |
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Why don't we detect some incoming asteroids/comets? |
If the object comes from the sunlit side of the earth (wasn't bright enough to detect) |
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What is the relationship between the size and frequency of impacts by asteroids/comets? |
Inversely proportional (bigger the object, less frequent the impact)
-small impacts happen almost daily |
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What are the effects of different impactors based on size? |
1) <10m (burns up in atmosphere) 2) 10 -100m (heat/blast for tens of km - nuclear weapon) 3) 100m - 1km (heat/blast over hundreds of km) 4) > 1km (tsunamis, global effects, extinctions) |
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What are some possible solutions for incoming asteroids? |
1) Nuclear weapons 2) Gravity tractor 3) Rocket motor 4) Focused solar energy |
