Science Ch 21 "The Universe"

Universe

All matter and space that exists

Galaxy

A cluster of stars, dust and matter

Plantary systems

Planets that are gravitationally bound in orbit around a star or stars

Light Year

Astronomical distance unit

Dark Energy

Invisible energy that fills the space between galaxies

Dark Matter

Hypothetical substance that doesn't reflect, emit or obstruct light

Ordinary Matter

Atoms made of protons, neutrons and electrons to form things that we are familiar with

Star

Massive celestial object made of plasma

Structure of the Universe

Planets, Stars, Planetary Systems, Galaxies

What is the Big Bang theory and how di the universe form?

The Big Bang Theory is how scientists believe the universe was created. It is the belief that the universe was created from an explosion or rapid expansion.

Graph the composition of the universe

Dark Energy 71.4%, Dark Matter 24%, Ordinary Matter (Atoms) 4.6%

What are the 3 major types of galaxies?

Elliptical, Spiral, Irregular

Elliptical Galaxy

Egg shaped, smooth & bright, old stars (appear red), most common

Spiral Galaxy

spiral shaped with long arms extending from the centre. often has a black hole in the centre. stars are continuously forming

Irregular Galaxy

No distinct. regular shape. Believed to have come from spiral or elliptical galaxies

How did our solar system form?

There was a molecular cloud then the sun began to form then protoplanetary disk began to form then the planets were formed.

What are the different types of stars and how does their brightness, temperature and size vary?

The four types of stars are the Main Sequence Star, the Red Giant, the Super Giant & the White Dwarf. Main Sequences brightness and luminosity the larger the star is. Supergiants are the biggest and are warm and very bright. Red Giants are large and bright. A White Dwarf is a small, hot, faint stars. The bigger the star the hotter and brighter it is.

Life of an average-sized star

Spends most of its life fusing hydrogen into helium in its core, eventually expanding into a red giant before shedding its outer layers and leaving behind a white dwarf

Life of a massive star

Spends most of its life fusing hydrogen into helium in its core, eventually it begins fusing helium and becomes a massive supergiant. Once the star cannot produce enough energy to overcome its gravity it explodes in a massive explosion called a supernova. If the core survives it turns in to a neutron star or a black hole.