The Universe and Galaxies

The universe is vast in size and very very old

COSMOLOGY• The study of the universe, its nature, its

origin and its evolution

Measuring the UniverseLight year: A unit of distance, not time. The distance light

travels in 1 year: about 10 trillion kilometers (6 trillion miles).

• This is the theory that states how the universe formed

• The Big Bang theory is our best current model for the origin of the universe. The Big Bang theory states that the universe began in a very hot, dense state that expanded and eventually condensed into galaxies.

Support of Theory

• Cosmic background radiation found to support the theory

• It comes from distant edges of the universe from objects whose temperature is thought to be constant with the Big Bang

https://www.youtube.com/watch?v=-dR26JmmaBM#t=21

•  The slight changes in the intensity of the CMB across the sky give us a map

of the early universe

Red Shift

• The universe is • This phenomenon is known as the Red Shift.

The color red of the spectrum of each galaxy is shifting or moving away

• The Doppler Effect: change in wavelength of light as an object is moving toward or away from you

• The farther away a galaxy is the faster it is moving

Red Shift

• When the light from a galaxy which is moving away from you is observed the  wavelength of the observed light appears longer, it moves towards the red end of the spectrum. This is called RED SHIFT.

http://physicsnet.co.uk/gcse-physics/red-shift/

Red Shift

Quasars• Quasars: Star-like, very bright,

extremely distant objects at the edge of the Universe that give off radio waves

• Oldest objects in the universe, they formed right after the Big Bang

• Give off a tremendous amount of energy and radiation

• By studying quasars you are actually studying the formation of the Universe

Dark Matter

• Dark matter accounts for 90% of the mass in the universe, it is invisible

• This is what makes the sky dark, it does not give off, reflect or absorb any light

http://www.speed-light.info/video_dark_energy.htm

Types of Galaxies• Spiral Galaxies: Spiral shaped with

normal spirals and barred spirals • Elliptical Galaxies: not flattened into a

disk shape, no arms, similar to a football in shape

• Irregular Galaxies: no distinct shape• Most galaxies are located in groups

rather than being spread throughout the universe

Galaxy types

Elliptical

Spiral

Irregular

Milky Way Galaxy• Side angle looks like a fried egg, flat

edges and bulging in the middle• Spiral shape with arms rotating off the

sides, circulates around the center bulge

• Center of galaxy has a high concentration of stars

• Our solar system is located in the arm of Orion (pg. 836)

They are out to get us!!