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Meteorites and Planets
For Exam 1 in my Meteorites and Planets class at IUB
53
Astronomy
Undergraduate 1
09/22/2015

Additional Astronomy Flashcards

 


 

Cards

Term
Meteoroid
Definition
A natural object of up to 100 m in diameter that is orbiting in space
Term
Meteor
Definition
The visual phenomenon associated with the passage of a meteoroid through the Earth's atmosphere
Term
Meteorite
Definition
A recovered fragment of a meteoroid that has survived transit through the Earth's atmosphere
Term
Iron Meteorites
Definition
Consist almost entirely of nickel-iron metal alloys, whereas stony meteroites are composed mostly of silicate and oxide minerals, although many also contain small metal grains
Term
Stony-iron Meteorites
Definition
Meteorites that have nearly equal porportions of metals and silicates
Term
Chrondite
Definition
One of the two categories to further determine a stony meteorite. This is a kind of cosmic sediment, an agglomeration of early solar system materials that has suffered little, if any, chemical change since its formation.
Term
Achrondite
Definition
The second category of stony meteorites. This is an ingenous rock, the product of partial melting (accompanied by changes in chemical composition) and crystallization.
Term
Falls
Definition
Meteorites that have fallen and then recovered
Term
Finds
Definition
Meteorites that were recovered but were not onserved to fall
Term
Micrometeorites
Definition
The smallest meteorites
Term
Interplanetary Dust Particles (IDPs)
Definition
Also known as micrometeorites and are the smallest meteorites
Term
Oriented Meteorite
Definition

When some of the melt streams along the sides to the posterior surface, where it collects and solidifies into a rouhgly textured mass and forms a conical shape 

 

[image]

Term
Regmaglypts
Definition
Depressions in the surface of some meteorites resembling thumbprints that form during atmospheric transit. Probably caused by the violent motion of air or selective melting and ablation of certain parts of the meteoroid.
Term
Fusion Crust
Definition
A layer of solidified melt glass coating the exterior. Such glassy surfaces are very thin and form when the outside is melted by the friction of the atmosphere and is cooled when the speed slows down.
Term
Retrograde Orbit
Definition
Moving in a direction contrary to practically all the bodies of the solar system
Term
Prograde Orbit
Definition
Moving in the same direction as other bodies in the solar system
Term
Terminal Velocity
Definition
Air resistance eventually slows most meteors to the highest velocity attainable by an object as it falls through air otherwise known as terminal velocity
Term
Cosmic Velocity
Definition
The velocity of an object that it had in space
Term
Strewn Field
Definition
The area where meteroites from a single fall are dispersed
Term
Meteorite Stranding Surfaces
Definition
Areas where meteorites are concentrated
Term
Paired Meteorites
Definition
Fragments of the same meteorites
Term
Hypervelocity Impacts
Definition
Meteors that retain some of their cosmic velocity on its way to the ground
Term
Craters
Definition
Depressions in the ground caused by hypervelocity impacts
Term
Asteroids
Definition
Massive meteoroids that carry tremendous amounts of kinectic energy and have potential to cause great devestation
Term
Astroblemes
Definition
The eroded remnants of ancient craters
Term
Near-Earth Objects (NEOs)
Definition
A swarm of asteroids and comets that surround the Earth
Term
Amor, Apollo, or Aten
Definition
Asteroids in near-Earth space are categorized as this depending on whether their orbits lie outside that of the Earth, overlap that of the Earth with peroids of greater than one year, or overlap that of the Earth with periods of less than one year
Term
Parent Bodies
Definition
Sources of meteorites and also NEOs
Term
Spectrophotometry
Definition

Analyzes the sunlight reflected off of the surface of asteroids, and can be used to indicate the average composition of the asteroid's surface 

 

 

Term
Albedo
Definition
The ratio of light reflected by a surface to the incident light; a measure of the efficency of the reflection proccess.
Term
Reflectance Spectra
Definition
The spectrums that are reflected from asteroidal surfaces
Term
Absorption Bands
Definition
A valley in a reflectance spectrum produced by absorption of certian wavelengths of energy by asteroid surface materials
Term
Chrondules
Definition
Millimeter-sized spherule of rapidly cooled silicate melt, found in abundance in chondritic meteorites
Term
Isotopes
Definition
Atoms of a given element that differ in mass due to the loss/gain of neutrons
Term
Radioactive Isotopes
Definition
Unstable isotopes which transform over time by loss of protons, neutrons, or electrons into more stable isotopes of other elements
Term
Radiogenic Isotope
Definition
The new isotope that has formed from a parent isotope
Term
Radionuclide
Definition
An unstable isotope
Term
Half-Life
Definition
The time interval required for half of the remaining atoms of a radioactive isotope to decay; this must be known for radiometric age determinations
Term
Isochron
Definition
A straight line on an isotope evolution diagram, defined by the isotopic compositions of related rocks or mineral grains from the same sample; the slope of this line gives the age of the rock.
Term
Mass Spectrometer
Definition
A sensitive instrument that measures the isotopic composition of a sample by separating ions of different mass using a large magnet to alter their trajectories
Term
Fission Tracks
Definition
A submicroscopic trail in a crystal traveled by a particle produced by rasdioactive decay; these can be used as a means of age determination
Term
Formation Interval
Definition
Meteorites must have formed within the first few million years of solar system history commonly known as the formation interval
Term
Cosmic Abundance
Definition
The chemical composition of the solar system
Term
Volatile Elements
Definition
An easily volatilized substance that condenses from a gas at low temperature. The Sun has more of these elements so meteorites differ from the chemical composition of the Sun in this regard.
Term
Groups
Definition
A chemical classification of chondrites; groups are identified with capital letters, for example, H or CV. Probably formed on the same parent body
Term
Clans
Definition

A related group of chondritic meteorites; inferred to have formed in the same region of the solar system. 

 

 

Term
Ordinary Chondrites
Definition
Term
Ordinary Chondrites
Definition
The most abundant clan
Term
Carbonaceous Chondrites
Definition
Always carbon-bearing, but actually misnamed when it was believed that they had much higher carbon contents than other chondrites
Term
Enstatite Chondrites
Definition
Named for their higher abundances of the magnesium silicate mineral, enstatite.
Term
Rumuruti and Kakangari Chondrites
Definition
Both named for the only meteorite falls of this type and may represent distinct clans but each contain only one recognized group.
Term
Oxidation
Definition
Loss of electrons resulting in the conversion of reduced species like iron metal into oxidized species like ferrous and ferric ions.
Term
Accretion
Definition
The clumping together of any cosmic sediment found in the area a chondrite was formed
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