Chapter 9 glossary terms

The galaxy that includes the solar system; appears as a hazy white band in the night sky

 A collection of stars, dust, gas and planets all held together by gravity

A collection of stars held together by gravity

A collection of 50 to 1000 stars; open clusters appear along the main band on the Milky Way

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

A small group of Galaxies (40) that include the Milky way

A gigantic cluster of 4 to 25 cluster galaxies that is hundreds of millions of light-years away

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

The study of the universe

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

The effect in which objects moving away from an observer have their wavelenghts lenghthened

The effect in which objects moving toward the observer have their wavelenghts shortened

The event that may have triggered the expansion of the universe 14 billion years ago

The radiation left over from the Big bang whcih fills the universe

The most abundant form of matter in the universe; inviasble to telescopes

A form of energy that makes up nearly 3 quarters of the universe; has the effect of increasing the expansion of the universe