Download Universe and Solar System Study Guide

Universe Study Guide
Name: KEY
The test on this unit will be given on Thursday, March 5th.
1. Scientific Theory: an explanation that is supports by repeated experimentation or testing. It has
evidence to back it up.
2. Geocentric Theory: theory that stated the Earth is at the center of the revolving planets and stars.
Proposed by ancient Greeks. This was not correct.
3. Heliocentric Theory: theory that states the Sun was the center of the revolving planets and stars.
Proposed by Nicholas Copernicus and later was proven by Galileo. THIS IS WHAT WE BELIEVE TODAY.
Revolution is the length of time required for a planet to make one complete trip around the Sun. Rotation
is the length of time required for a planet to make one complete turn on its axis.
Our Solar System:
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Our Solar System was formed from a collapsing cloud of gas and dust called a nebula.
Our Solar System is divided into inner and outer planets.
Inner Planets are closest to the sun and include Mercury, Venus, Earth, and Mars.
Outer Planets are farthest from the sun and include Jupiter, Saturn, Uranus, Neptune, and dwarf
planet Pluto
8. An asteroid belt divides the inner and outer planets.
9. Comparison of the inner and outer planets
Inner Planets (terrestrial – terra = Earth)
1. Smaller Planets
2. Rocky Surface
3. No to few moons
4. Atmospheres are made of heavier
elements
5. Faster orbits around the sun
Outer Planets: Nickname – gas giants
1. Larger Planets
2. gas surfaces
3. Many moons
4. Atmospheres are made of lightweight elements
5.Slower orbits around the sun
10. Only Earth has the necessary conditions to support human life such as oxygen, liquid water, and
perfect temperatures. The pull of gravity on Earth is a direct result of the mass of Earth. The
ozone layer in the Earth’s upper atmosphere is important to living organisms because it absorbs
harmful ultraviolet radiation from the Sun. Mercury has a large range of temperatures because the
planet lacks an atmosphere to hold heat. Venus is sometimes called Earth’s twin because it is the
same size and density. Venus also has the highest surface temperature because its atmosphere
has thick clouds and carbon dioxide. Mercury would NOT a gas giant because it is dense and rocky.
Mars may once have had a warmer climate because it has features like dry river beds. Mars may
have had surface water or flowing rivers at one time. Uranus is considered a gas giant because it
has a deep, massive atmosphere. Jupiter has a hurricane-type cloud known as the Great Red Spot.
The astronomical unit is most useful for measuring distances within the solar system.
Other Small Bodies in the Solar System:
11. Comets: a small body of ice, rock, and cosmic dust that follows an elliptical orbit around the sun. It
gives off gas and dust in the form of a tail as it passes close to the sun. The tail always points away
from the sun due to solar winds.
12. Asteroids: a small, rocky object that orbits the sun, usually in a band between the orbit of Mars
and Jupiter.
13. Meteoroid: small, rocky body that travels through space.
14. Meteor: bright streak of light that results when a meteoroid burns up in the Earth’s atmosphere.
Sometimes called a “shooting star”
15. Meteorite: A meteoroid that reaches Earth’s surface without burning up completely.
REMEMBER:
meteorOid is in Outer space
Meteor is a meteoroid minus the oid (oid is burning in the atmosphere)
meteorITE has taken a bITE out of the Earth
Planets or moons with atmospheres have fewer impacts because the air in the atmosphere slows and burns up small
objects.
Stars begin to glow when the neutrons in the star begin to spin.
Beyond our Solar System:
16. Galaxies: a collection of stars, dust, and gas bound together by gravity.
17. Our solar system is part of the Milky Way Galaxy.
18. It is spiral in shape. We are located about 2/3 of the way out in one of the curved arms. The three
types of galaxies identified by Edwin Hubble are spiral, elliptical, and irregular.
Formation of the Universe:
19. Big Bang Theory: theory that states the universe began with a tremendous explosion where all
matter and energy was concentrated. The universe is expanding outward. According to this
theory, the universe is about 13.7 billion years old. One way scientists calculate the age of the
universe is measure the distance from Earth to various galaxies.
Largest to Smallest
Universe, Galaxy, Solar System, Sun, Planets