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Astronomy Unit Test Study Guide
Universe, Galaxies, and Stars:
1. Put these terms in order from largest to smallest:
Milky Way Galaxy, Sun, Solar System, Universe, Earth, Nebula, Local Group, Hubble telescope
Universe, local group, Milky Way Galaxy, Solar System, Nebula, Sun, Earth, Hubble Telescope
2. What happens to the gravitational force between two objects if the distance between them doubles? Explain
why.
The gravitational pull between then will decrease.
3. How are an object’s mass and gravity related?
The more mass an object has, the stronger it’s gravity.
4. Explain the life cycle of our sun starting with its formation to its death. Be sure to use the following terms:
nebula, main sequence, white dwarf, red giant
A star begins to form in a nebula of gas and dust. After it is born as a protostar, it will spend most of its life as
a main sequence star, before expanding into a red giant. Eventually our sun will die out as a white dwarf and
then stop shining and become a black dwarf.
5. Explain the big bang theory. What evidence is there to support it?
The Big Bang Theory explains how the Universe began very small and dense and eventually expanded outward
13.7 billion years ago. Cosmic Background Radiation is radiation left over throughout space left over from the Big
Bang, which they have diagramed on the WMAP. Scientists know that the universe is still expanding today. They
believe that eventually the universe might expand so fast that it rips, reverse and shrink, or continue to expand
the way it is now.
Solar System:
6. How do planets form? Explain.
Terrestrial: Colliding rock and dust
Gas Giant: colliding gas and dust
7. List the four terrestrial planets. What makes them “terrestrial?”
Mercury, Venus, Earth, Mars
These planets are dense, small and made of rock
8.
List the four gas giant planets. What makes them “gas giants?”
Jupiter, Neptune, Uranus, Saturn
These planets are large and made of gas.
9.
Which planets have more moons and why? Explain!
The gas planets because they are larger and attract smaller objects with their gravity.
10. The Sun is much larger than the Moon. Explain why they appear the same size from Earth?
The sun and moon appear to be the same size because the sun is much farther away from Earth than the
moon is.
11. Define inertia and gravity. If the force of gravity between the Earth and the sun were greater than Earth’s
inertia, what would happen to Earth? Explain your answer.
Inertia- objects tendency to move forever in a straight line at constant speed.
Gravity- Force attracting an object to another object.
The Earth would be pulled into the sun and eventually collide.
12. Explain what is occurring in the picture below:
1. Nebula of gas and dust.
2. Nebula begins to spin and flatten into a rotating disk.
3. Gravity causes gas and dust to collide and form gas planets.
4. Gravity causes rock and dust to collide and form rocky planets.
5. Solar System is formed.
Motion:
13. What two factors affect a planets revolution?
Gravity and Inertia
14. What planet would revolve the slowest around the Sun and why?
Neptune takes the longest to revolve around the sun because it has the biggest orbit around the sun. (It is the
farthest planet)
15. Explain the difference between revolution and rotation.
Revolution is the time a planet orbit around the sun.
Rotation is a time it takes a planet to spin on its axis.
16. Answer the questions below:
a. How long does the Earth take to rotate?
1 day = 23 hours, 56 mins, 4 secs = about 24 hours
b. How long does the Earth take to revolve around the Sun?
1 year = 365.26 days = about 365 days
c. How long does it take for the Moon to revolve around the Earth?
29 days = about 1 month
17. Draw a model of the relationship between the Sun, Earth and Moon.
Sun
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Seasons:
18. What is the summer solstice? What is the date?
The summer solstice is the season of summer. It is the longest day of the year (June 21)
19. What is the winter solstice? What is the date?
The winter solstice is the season of winter. It is the shortest day of the year (Dec 21)
20. What causes the seasons? Explain your answer.
The seasons are caused by the tilt of the Earth’s axis as it revolves around the Sun. This changes the angle of
the sun’s radiation.
21. Draw a model below of the path of the Sun in the winter and in the summer. Explain the difference between
the paths and why it occurs.
During the summer the sun’s path is higher in the sky and longer, so days are longer and warmer.
During the winter the sun’s path is lower in the sky and shorter, so days are shorter and colder.
22. Label the diagram below with the seasons:
Spring
Summer
Winter
Fall
Moon Phases & Eclipses:
23. Draw a model of the Moon phases below. How long does it take between 1 full moon and the next?
29 days
24. Explain how the Moon lights up. Draw a picture if it helps!
The moon reflects the light from the sun because it is non-self-luminous.
25. Draw a model of a solar eclipse and explain what is occurring. Be sure to include the phase of the moon that
must be present for it to happen.
During a solar eclipse, the Sun, moon and Earth are perfectly aligned and the Moon crosses in front of the sun,
casting a shadow on a part of the Earth. It must be a new moon phase.
26. Draw a model of a lunar eclipse and explain what is occurring. Be sure to include the phase of the moon that
must be present for it to happen.
During a lunar eclipse, the Sun, Earth and moon are perfectly aligned and the Earth crosses in front of the sun,
casting a shadow on the moon. It must be a full moon phase.