Origin of the Universe, part 1 Vocab

wavelength

the distance from the peak of one light or sound wave to the peak of the next

frequency

the number of complete wavelengths that pass a point in a given time; directly corresponds to energy level

redshift

shift of light to a longer wavelength as it moves away

blueshift

shift of light to a shorter wavelength as it moves closer

Is the universe expanding, contracting, or staying the same?

expanding

Are most galaxies moving toward or away from each other?

away

Are most galaxies in redshift or blueshift?

redshift

How does the pitch of a sound change as it gets closer to you?

it gets higher (shorter wavelength)

How does the pitch of a sound change as it gets farther away from you?

it gets lower (longer wavelength)

How does the wavelength of light change as an object moves closer to us?

it gets shorter

How does the wavelength of light change as an object moves away from us?

it gets longer

Which color of visible light has the shortest wavelength?

blue/purple

Which color of visible light has the longest wavelength?

red

electromagnetic spectrum

all forms of radiation (both visible and invisible) including: (longest wavelength/lowest energy) radio waves —> microwaves —> infrared —> visible light —> ultraviolet —> x-rays —> gamma waves (shortest wavelength/highest energy

continuous spectrum

“white” light emitted by a hot, dense star that includes all wavelengths of light in a certain range

absorption spectrum

When starlight passes through a cloud of gas, some of the light is absorbed and some is transmitted through the gas. The wavelengths of light that are absorbed depends on what elements and compounds in the gas cloud. Dark lines in the spectrum correspond to wavelengths that are absorbed by the gas.

emission spectrum

Starlight can heat up a cloud of gas, exciting the atoms and molecules within the gas, and causing it to emit light. The spectrum of light that a cloud of gas emits depends on its temperature, density, and composition. An emission spectrum consists of a series of colored lines that correspond to wavelengths emitted by the glowing gas.

spectral lines

Dark or bright lines in a spectrum that result from the absorption or emission of light; used to identify elements and molecules in stars, galaxies, and gas clouds.