The galaxy that includes the solar system; appears as a hazy white band in the night sky
Galaxy
A collection of stars, dust, gas and planets all held together by gravity
Star cluster
A collection of stars held together by gravity
Open clusters
A collection of 50 to 1000 stars; open clusters appear along the main band on the Milky Way
Globular clusters
A collection of 100,000 to 1,000,000 stars that is arranged in a spherical shape and are found in the centre of the Milky Way
Local group
A small group of Galaxies (40) that include the Milky way
Supercluster
A gigantic cluster of 4 to 25 cluster galaxies that is hundreds of millions of light-years away
Shapes of galaxies
Spiral- A galaxy that looks like a spiral with extended arms comming out of it; we are locates in a spiral galaxy
Oliptical- A galaxy that looks circular or ellipse that contains some of the oldest stars in the galaxy
Irregular- A galaxy that dose not have a distictive shape but contains new and old stars
Cosmology
The study of the universe
Doopler effect
The change in frequency of a light source due to its motion relative to an observer; also, the change in pitch of a sound due to the motion of the source relative to an observer
Redshift
The effect in which objects moving away from an observer have their wavelenghts lenghthened
Blueshift
The effect in which objects moving toward the observer have their wavelenghts shortened
Big bang
The event that may have triggered the expansion of the universe 14 billion years ago
Cosmic microwave radiation
The radiation left over from the Big bang whcih fills the universe
Dark matter
The most abundant form of matter in the universe; inviasble to telescopes
Dark energy
A form of energy that makes up nearly 3 quarters of the universe; has the effect of increasing the expansion of the universe