Study Guide Answers
1. What is the difference between geocentric
and heliocentric?
•Geocentric: Earth is the center
of the universe
•Heliocentric: Sun is the center
of the universe. This is what we
currently believe in!
2. What did Copernicus believe about the
system of planets?
1) Found evidence for the idea of
a heliocentric system.
2) Said that the moon revolved around
the earth.
3)The earth revolved around
the sun to cause a year.
3. What did Ptolemy believe about the system
of planets?
He believed that the EARTH was
at the center and the sun &
planets revolved around in
GEOCENTRIC
4. What did Brahe and Kepler prove?
Brahe: First to predict that orbits
were not circular.
Kepler: Assistant, He used
Tycho’s data to
figure out that the planets’ orbits
are not round but are ellipses.
5. What discoveries did Galileo make that supported
Copernicus’ views of the solar system? And what did he use to
make these discoveries?
• One of the first to turn the
Telescope to the sky to study
astronomy.
• Saw that Venus went through
phases like the moon –
indicating change in angle like
moon phases.
Continued
Galileo improved the telescope to look at the
sky. He discovered:
• Venus goes through phases like the moon.
• He saw that Jupiter had 4 moons revolving
around it.
Galileo’s evidence convinced others that
Copernicus’ ideas were correct.
6. What two forces keep the planets in orbit
around the sun?
Inertia
&
Gravity
7. What is the difference between inertia and gravity?
What would happen if one or the other was not
present?
Inertia: The tendency of a moving
object to continue in a straight line or a
stationary object to remain at rest. Moon
would crash
Gravity: The force of attraction
between objects - the force depends on
the mass of the two objects and the
distance between them. Moon would
float away
Continued
Without gravity, the
planets would fly off
into space.
Without inertia, the
moon would fall to
Earth, or the planets
to the sun.
8. List the planets in order from the sun out.
Mercury
Venus
Earth
Mars
Jupiter
Saturn
Uranus
Neptune
9. What do the first 4 inner planets have in
common
They are small, and have rocky
surfaces
Not as much Hydrogen and
Helium because they are closest
to the sun.
Mercury, Venus, Earth, Mars
10. What do the first 4 outer planets have in
common
Gas Giants
They are much larger than Earth and
do not have solid surfaces.
The gas can’t escape because these
planets have very STRONG
GRAVITY
Jupiter, Saturn, Uranus, and Neptune
Continued
• They are made of gas.
• They have deep atmospheres held by strong
forces of gravity.
• They are very large.
• They have rings.
• They have more than two moons.
11. What makes Earth unique and different
from the other planets?
• Liquid water.
• A protective
atmosphere.
12. How are Venus and Earth alike?
Relatively the same size and
density
13. What is the difference between a
comet, asteroid, and meteoroid?
Comet: small body of ICE, rock and cosmic
DUST that follows a narrow, elliptical orbit
around the sun; gives off gas and dust in
the form of a tail when it passes close to
the sun.
Asteroid: small, rocky object that orbits the
sun, usually in a band between Mars and
Jupiter.
Meteoroid: a relatively small body, rocky
body that travels through space.
14. What is the difference between
meteoroid, meteor, meteorite?
Meteoroid: a relatively small body, rocky
body that travels through space. They are
smaller than asteroids, and can be as small
as a speck of dust.
Meteor: “shooting star” a bright streak of
light cause by a meteoroid burning in the
atmosphere.
Meteorite: when a meteor makes it to
Earth’s surface.
15. Comets’ orbits are what
shape?
Comet’s orbits are long, narrow ellipses.
16. What affects the revolution
time of each planet?
According to Kepler’s third law of
planetary motion, “The farther away
from the sun a planet is, the longer it takes
for the planet to orbit the sun.”
17. Which object or objects
would have the greatest
period of revolution?
A comet
.
18. What is the asteroid belt and where is
it located?
wide region of small, rocky
bodies that is located between
the orbits of Mars and Jupiter
19. What is the theory that explains the formation
of our solar system? Explain the theory.
The theory that explains the formation of our solar system is the Nebular
Theory.
Scientists believe that the solar system was formed when a cloud of gas and
dust in space was disturbed, maybe by the explosion of a nearby star (called
a supernova). This explosion made waves in space which squeezed the cloud
of gas and dust. Squeezing made the cloud start to collapse, as gravity pulled
the gas and dust together, forming a solar nebula. Just like a dancer that
spins faster as she pulls in her arms, the cloud began to spin as it collapsed.
Eventually, the cloud grew hotter and denser in the center, with a disk of
gas and dust surrounding it that was hot in the center but cool at the edges.
As the disk got thinner and thinner, particles began to stick together and
form clumps. Some clumps got bigger, as particles and small clumps stuck to
them, eventually forming planets or moons . Near the center of the cloud,
where planets like Earth formed, only rocky material could stand the great
heat. Icy matter settled in the outer regions of the disk along with rocky
material, where the giant planets like Jupiter formed. As the cloud continued
to fall in, the center eventually got so hot that it became a star, the Sun
http://www.windows.ucar.edu/tour/link=/our_solar_system/formation.html
20. How old is our solar
system?
About 4.6 billion
Years
21. What two elements is our solar
system mainly composed of?
Hydrogen
&
Helium
22. Which planet’s atmosphere is
trapping carbon dioxide and causing the
Greenhouse Effect?
Venus is the hottest planet in the solar system
because its carbon monoxide atmosphere
traps the heat from the sun.
23. Which other planet is believed to have once
had running water and has been shaped by the
same forces as Earth? List the forces that have and
continue to shape Earth’s surface.
Scientists believe that Mars once had running
water.
The forces that shape Earth’s surface are
weathering, erosion and deposition.
24. List each astronomer and their
contribution to modern astronomy.
Ptolemy: Geocentric theory
Copernicus: Heliocentric theory
Brahe: 20 years of accurate observations and
measurements.
Kepler: with Brahe’s data discovered orbits are
elliptical. Laws of planetary motion.
Galileo: with his telescope proved Copernicus
was correctwhen he saw the phases of Venus
and the moons of Jupiter.
Newton: discovered gravity and inertia, which
explained why planets remain in their orbits.