Ch 13+14 Flashcards
Asteroid Belt
Asteroids found in broad space between Mars + Jupiter; most have orbital period of 3.3 to 6 years
Ceres
Largest asteroid; Been reclassified since then as a dwarf planet
5 Largest Asteroids
Ceres, Pallas, Juno, Vesta, Hygiea
Dark Asteroids / C-Type
Reflectivity of only 3 to 4%; make up majority; composed of silicates mixed with dark, organic carbon
S-Type Asteroids
Higher reflectivity; stony / silicate composition
M-Type Asteroids
Composed of metal
Vesta
Brightest asteroid with reflectivity of 30%
Phobos + Deimos
Small moons of Mars that are probably captured asteroids
Eros
S-Type asteroid; made of chemically primitive materials; has good deal of loose surface material
NEOs
Near-Earth Objects: any comets that come close to our planet
NEAs
Near-Earth Asteroids
Comet
relatively small chunk of icy material that develops an atmosphere as it approaches the Sun; faint, nebulous tail
Comet Orbits
unpredictable appearances
Comet Halley
returns at average intervals of 76 years
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
Comet’s Nucleus
Nucleus is the real comet; made of ancient icy material and hydrocarbons and silicates
Comet’s Atmosphere
Ice vaporizes near Sun absorbing energy; Gas released in spurts; Tail is extension of atmosphere
Dust Tail
Made of dust and curves a bit
Ion Tail
Made of gas and is pushed more directly outward from the Sun
Rosetta Mission
Goal was to follow an incoming comet’s orbit and follow it as it approaches the Sun
Kuiper Belt
Large area of space beyond Neptune that is the source of many comets; short period comets
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
