Unit 1- universe (topic 1)

Goldilocks principle

The idea that earths is “just right” for life — not too hot, not too cold

Planetary System

A group of planets orbiting a star (like our Solar System)

Galaxy

A large collection of stars, gas, qnd dust held together by gravity

Spiral Galaxy

Galaxy with spiral arms; example: the milky way

Elliptical Galaxy

Shaped like a flattened ball with older stars

Irregular Galaxy

No definite shape; contains young stars and gas

Luminosity

The brightness of a star

HR diagram

A chart showing the relationship between a stars brightness and tempature

Nebula

A cloud of gas and dust where stars form

Protostar

A baby star inside a nebula

Main sequence star

A stable, middle aged star like our sun

Red giant

A large, cool star nearing the end of its life

White dwarf

The small, hot core left after a red giant losses its outer layer

Supernova

An explosion that occurs when a massive star dies

Neutron Star

A very dense star left after a supernova

Black hole

An object with gravity so strong that not even light can escape

Pulsar

A spinning neutron star that sends out radio waves