Universe

One exciting thing from universe is the recognition of how vast the universe is - beyond our comprehension.

Key Words in Universe

Word	Definition
Star	a massive object in space that creates and radiates energy.
Nuclear Fusion	Stars produce and emit energy by nuclear fusion. In nuclear fusion, smaller atoms are joined together to produce energy
Luminosity	brightness of a star.
Big Bang	the universe started as a small volume and expanded rapidly.
Cosmic Background radiation	is the electromagnetic radiation left over from the formation of the universe.
Doppler Effect	Galaxies are moving away from Earth. This moving away shows up as a redshift on spectrum.
Galaxy	a huge group of stars held together by gravity.
Milky Way Galaxy	our sun is a part of the Milky Way Galaxy.

Key Things to Know in Universe

Red shift = moving away from you (universe is expanding), blue or violet shift = moving toward you.
The universe began with a big explosion--"The Big Bang." Proof = cosmic background radiation from the explosion.
Our solar system is located on one of the outer arms of our Milky Way Galaxy.

Example 1

Which object forms by the contraction of a large sphere of gases causing the nuclear fusion of lighter elements into heavier elements?
(1) comet (3) star
(2) planet (4) moon

Star, like our sun, produces and gives off energy by nuclear fusion. Nuclear fusion fuses ligher atoms into a larger atom and produces energy as a result of the fusion.

Exercises

1. Evidence that the universe is expanding is best provided by the
(1) red shift in the light from distant galaxies
(2) change in the swing direction of a Foucault pendulum on Earth
(3) parallelism of Earth’s axis in orbit
(4) spiral shape of the Milky Way Galaxy