Chapter 3 Flashcards
cosmic address
earth is in the solar system which is in the milky way galaxy which is in the local group which is a part of the local supercluster which is in the universe/cosmos
dark matter
matter that we infer to exist due to its gravitational effects but from which we haven’t detected any light; it apparently dominates the total mass of the universe
dark energy
the name sometimes given to energy that could be causing the expansion of the universe to accelerate
the big bang
the scientific theory of the universe’s earliest moments, states that all the matter in our observable universe came into being at a single moment in time as an extremely hot, dense mixture of subatomic particles and radiation; prediction that universe’s chemical composition should be about 3/4 hydrogen, 1/4 helium and observations show that this is a close match to the overall chemical composition of the universe.
nuclear fusion
process where two (or more) smaller nuclei slam together and make one larger nucleus; 4 hydrogen nuclei are needed to make 1 helium nucleus; stars do this a lot
observable universe
the portion of the entire universe that we can potentially observe- consists only of objects that lie within 15 billion light-years of earth
terrestrial planets
earthlike; made mostly of rock and metal; smaller in size and mass; higher density; solid surface; few if any moons and no rings; closer ot the sun and closer together with warmer surfaces
jovian planets
larger in size and mass, lower density; made mostly of hydrogen, helium, and hydrogen compounds; no solid surface; rings and many moons; farther from the sun (and farther apart), with cool temperatures at cloud tops
asteroid
made of metal and rock mostly
comet
made mostly from rock and ice
asteroid belt
region where most asteroids orbit; between Mars and Jupiter
Kuiper belt
region beyond Neptune; where Pluto and Eris + other small objects
Oort cloud
in the Kuiper belt; trillions of comets orbut the Sun with random inclinations, orbital directions, and eccentricities
Nebular Theory
asteroids and comets are leftovers; solar nebula was hottest near protostar, coolest farther away; “frost line” defined as the distance from protostar at which ices could condense; asteroids and terrestrial planets formed inside frost line; comets and jovian planets formed past the frost line; after formation jovian planets can migrate (through gravitational intereractions) into the inner solar system of some stars
charge of a proton?
positive
charge of an electron
negative
charge of a neutron
neutral
ion
atoms that lose or gain electrons and then obtain a net electrical charge.
atomic number
number of protons
atomic mass
number of protons and neutrons
isotope
version of an element with different number of neutrons
ionization
stripping of electrons; changing of atoms into plasma
allowed transitions
changes corresponding to a change in energy levels
molecule
two or more atoms
dissociation
breaking of molecules into atoms
kinetic energy
energy of motion; examples: falling rocks, orbiting planets
radiative energy
energy carried by light; ex: light molecules in our eyes that allow us to see. sun’s warming of the earth’s surface
potential energy
stored energy; ex: rock perched on a ledge has gravitational potential energy, gasoline contains chemical potential energy that can be converted into kinetic energy of the moving car.
wavelength
distance between adjacent peaks of the electric or magnetic field
frequency
the rate at which the electric and magnetic fields change; unit is Hz
energy
what makes matter move
speed of light
300,000 km/s, 186,000 mi/s
photon
“piece” of light
accretion
the process by which particles stick together and grow larger
order of electromagnetic spectrum from longest to shortest
radio, IR, visible, UV, x-ray, gamma
continuous spectrum
a spectrum of light that spans a broad range of wavelengths without interruption by emission or absorption lines
emission spectrum
a spectrum that contains emission lines
absorption spectrum
a spectrum that contains absorption lines
thermal radiation
the spectrum of radiation produced by an opaque object that depends only on the object’s temperature;
polarization
the direction in which a light wave is vibrating; reflection can change the polarization of light
