Space Flashcards
Astronomical Unit
Mean distance of the earth to the sun
Big Bang Theory
The theory that the universe originated as a small, dense and hot region
that expanded and cooled forming the structures in the universe we see today
Doppler Effect
The apparent change in the wavelength of a wave as the source moves relative to an observer
For a source moving away the wavelength increases, for a source moving towards the observer the wavelength decreases
Dark Energy
An energy that is responsible for the acceleration in expansion of the universe
which cannot be explained by any observable energy and so must be dark
Dark Matter
Certain observations of galaxies and their dynamics shows that they are far more massive than they appear to be with just the matter we can observe leading to the
theory of dark matter to make up the rest of the unobservable mass
Giant Star
A large star with a higher luminosity than a main sequence star and a broad
temperature range
Hertzsprung-Russell Diagram
Visual representation of the lifecycle of a star
A plot of luminosity against temperature
Hubble’s Law
The speed of a galaxy moving away from ours is proportional to its distance away from us
The constant of proportionality is Hubble’s constant
Light Year
Distance travelled through space by a photon in a year
Luminosity
The total power radiated by a star
Main Sequence Star
A star that sits on the central band of stars on a Hertzsprung-Russel diagram where temperature increases with luminosity
Standard Candle
Objects of known luminosity used as references to measure other stars and to measure the distance to stars
Parallax
The change in position of an object depending on the viewing angle, this can be used to estimate the distance to a star based on how much it moves relative to the background of stars when the earth has moved half an orbit
Parsec
Unit of distance, the distance to a star whose parallax angle is 1 arcsecond
Redshift
The shift in light of distant galaxies due to all galaxies moving away from each other, the larger redshift of distant galaxies is due to these galaxies moving away at a faster rate
Supergiant Star
Very large luminous stars with a large temperature range of 3500-20000K
White Dwarf
A dense start with similar mass to the Sun and similar size to the Earth
Final stage of a low mass star’s life with low luminosity
