Describe what happened after the big bang, and how that led to the formation of galaxies.
- the universe began to expand at a constant rate
- the explosion caused matter to initially be distributed inhomogenously
o lumpiness; wasn’t smooth
- over time, lumps of denser matter became centers of high gravity and began to grow
- eventually the lumps became large group of stars and eventually galaxies
o large groups of stars are called galaxies
Explain why the solar system rotates.
- because of leftover momentum from the solar nebula that all the planets and the sun formed from
Describe the formation of the solar system, including the formation of the sun, the rocky inner
planets and the gaseous outer planets.
- a nebula forms from hydrogen helium and heavier elements left from the big bang
- the nebula, under the influence of gravity, condenses into a swirling disc, with a central ball
surrounded by rings
o as it condenses, it begins to spin
- ball at center grows dense and hot enough for fusion (two hydrogen atoms get together to form
o once fusion begins, this becomes the sun
- in the rings, dust particles collide and stick together, forming planetesimals
- planetesimals grow into the proto-Earth
o as it continues to grow, the interior heats up and becomes soft
- as the proto-Earth gets bigger, gravity reshapes it into a sphere
o interior differentiates
more dense iron-nickel metal moves into core
less dense rock moves outwards into crust
Explain the theory for the formation of the moon.
- soon after Earth forms, a small planet, about the size of Mars, collides with it
o Earth has iron core and so did the body that collided with it
o body added iron to earth and some rocky debris got sent into space
- debris formed a ring around the planet
o the Moon formed from the ring of debris
Know the difference between the following: universe, galaxy, solar system.
o everything we can see, all the galaxies
o cluster of stars
- solar system
o planets which are orbiting around a single sun
Know the composition of the sun and the process that causes it to produce heat.
- the sun
o composed of hydrogen and helium
o edges of sun is called corona