OGT:Chapter Eight

Origins Of The Universe

Astronomy Study of stars and planets

Aristotle Earth is center of the universe (geocentric). Sun, planets and stars rotated around the earth.

Copernicus proved planets revolve around Earth (heliocentric).

**Science discovery is based on the knowledge you have at the time

Telescopes Add To Knowledge1600’s Allowed scientists to view motion Sir Isaac Newton had the idea (hypothesis)

that objects attract each other by a natural force (gravity). Force pulls objects to ground Force attracts bodies across space Gravity decreases with distance Gravity increases with mass

Gravity is proportional Increase mass, increase gravity Decrease distance, decrease gravity

Newton’s Laws Added math to science Work showed that the movement of planets,

asteroids and comets are all determined by gravity

Moon has less mass which=less gravity=the moon has 1/6 the gravity of the earth.

If you weighed 180 pounds on earth, how much would you weigh on the moon?

A Star Is Born Telescopes help measure the light rays to

determine composition Most stars are made up of H and He Nuclear Fusion creates the star (atoms are

slammed together and create energy in the form of heat and light)

Nebula Star “factory” Gravity pulls dust and gas together Increased “glob” of dust and gas begins to

spin Pressure causes fusion (see above) Energy is released

Types of Stars Red Giant—older star (sun) Supernova—core is hot enough to create iron

helium, hydrogen and carbon Explosion occurs when core collapses—only a

few have been seen (chance) As cools becomes dwarf or black hole

The Big Bang Theory about the beginning of the universe

Stars and planets emit light (spectra)—it shows that the universe is expanding (red shift)

13-15 billion years ago One huge explosion hurled things into space Cooling of material allowed H and He to combine

and form first atoms

Milky Way Our galaxy (there are millions) There are spiral galaxies, bar galaxies, and

elliptical galaxies