Ch 13+14 Flashcards by Joanne Lee

Asteroid Belt

Asteroids found in broad space between Mars + Jupiter; most have orbital period of 3.3 to 6 years

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Ceres

Largest asteroid; Been reclassified since then as a dwarf planet

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5 Largest Asteroids

Ceres, Pallas, Juno, Vesta, Hygiea

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Dark Asteroids / C-Type

Reflectivity of only 3 to 4%; make up majority; composed of silicates mixed with dark, organic carbon

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S-Type Asteroids

Higher reflectivity; stony / silicate composition

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M-Type Asteroids

Composed of metal

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Vesta

Brightest asteroid with reflectivity of 30%

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Phobos + Deimos

Small moons of Mars that are probably captured asteroids

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Eros

S-Type asteroid; made of chemically primitive materials; has good deal of loose surface material

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NEOs

Near-Earth Objects: any comets that come close to our planet

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NEAs

Near-Earth Asteroids

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Comet

relatively small chunk of icy material that develops an atmosphere as it approaches the Sun; faint, nebulous tail

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Comet Orbits

unpredictable appearances

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Comet Halley

returns at average intervals of 76 years

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Short-period Comets

Comets returning in a time measurable in human terms; short-period comets have had orbits changed by going too close to giant plants

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Comet’s Nucleus

Nucleus is the real comet; made of ancient icy material and hydrocarbons and silicates

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Comet’s Atmosphere

Ice vaporizes near Sun absorbing energy; Gas released in spurts; Tail is extension of atmosphere

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Dust Tail

Made of dust and curves a bit

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Ion Tail

Made of gas and is pushed more directly outward from the Sun

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Rosetta Mission

Goal was to follow an incoming comet’s orbit and follow it as it approaches the Sun

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Kuiper Belt

Large area of space beyond Neptune that is the source of many comets; short period comets

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Oort Cloud

Reservoir of ancient icy objects from which comets are derived; long period comets

What obscures vision of meteor streaks?

Moon, street lights, cell phone screen, etc.

Meteor Showers

Particles of dust that are leftover from comets that come close to Earth; don’t survive flight into atmosphere

Fireball

Much brighter tail produced nu meteors size of gold balls

Radiant

Place in sky where parallel paths of dust particles & pebbles that make up meteor showers come towards us from

Perseid Shower

Appears each year for about 3 nights near Aug 11

Why are shooting stars streaks?

Heat & friction as it burns up in Earth's atmosphere

Falls

We search the area beneath the point where a fireball burned out to recover fallen meteorites

Finds

People find unusual-looking rocks that turn out to be meteoritic

Iron Meteor

Nearly pure nickel-iron

Stone Meteor

Silicate, rocky meteorite

Stony-Iron

Combination of both iron + stone

Differentiated Meteorites

Fragments of larger parent bodies that were molten before broken up, allowing denser materials to sink to their centers

Primitive Meteorites

Made of materials that were not subject to great heat or pressure since formation; parent bodies are asteroids

Carbonaceous Meteorites

Contain carbon, organic molecules, some chemically bound water; i.e. Murchison & Allende

Solar Nebula

rotating cloud of vapor and dust that the solar system formed out of cloud contracted under its own gravity

Spin Rates

Poles: Slow Equator: Faster

Formation of Solar System

(1) Solar Nebula --> Material fell toward center (2) Collapsing nebula began to rotate faster through conservation of angular momentum (3) Proto-Sun formed as hot dense center (4) Contraction of collapsed cloud of gas/dust contracted to form Sun (5) Sun surround by spinning disk of dust & vapor --> Planetismals --> Planets

Survivors of Solar Nebula

Meteorites, comets, asteroids

Spectroscopy

High-resolution helped yield many planet detections

Doppler Effect

Let's you measure star's radial velocity; Red if away

Transit Technique

Astronomers detect planet from measurements of change in brightness of star over long periods of time

"Baked Potato" Effect

Larger the planet or moon, the more likely it is to retain its internal heat and cools more slowly

Geologically Active Planets

Earth + Venus; Venus has "blob tectonics"

"Blob Tectonics"

Hot material from below bursts through surface leading to coronae, pancake volcanoes

Olympus Mons

On Mars, twice as high as Mt. Everest

Volcano Formation on Earth

Crustal Plates don't stop moving long enough to let large volcano grow, instead we get rows of volcanoes

Volcano Formation on Mars

Crust remains stationary so single volcano can grow for hundreds of millions of years + less surface gravity

Why do planets have spherical shapes?

Larger objects are pulled by gravity to have a more "efficient shape" -- asteroids can be potato shaped

Geological Activity on Terrestrial Planets

Level of activity is proportional to mass; Greater for Earth + Venus, less for Mars

Venus' Atmosphere

Runaway greenhouse effect led to permanent loss of water

Mars' Atmosphere

Had thick atmosphere of water but temp dropped and it froze because CO2 for greenhouse effect was lost