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Earth Science Vocabulary
First Nine Weeks
Unit 4 Astronomy - Key
Part I: Define the following terms
1. solstices - the longest and shortest days of the year
2. equinoxes - times of the year when the sun is located directly above
the equator so that day and night are of equal length around the world
(March 21 and September 22 – 23)
3. Apollo 11 - the 1st manned landing on the moon
4. galaxy - billions of stars grouped together
5. stellar evolution - the stages of development and duration of stars,
some of which appear on the H – R diagram
6. rotation - the turning motion of an object on its axis
7. lunar eclipse - occurs when Earth blocks sunlight from the moon’s
surface
8. Milky Way - the name of the galaxy to which our solar system belongs
9. asteroids - fragments of matter similar to planetary matter that orbit
between Mars and Jupiter
10. Big Bang Theory - the most accepted theory for the origin of the
universe
11. solar system - the sun and everything that revolves around it
12. comet - members of the solar system made of ice, gas, and dust
13. nebula theory - the solar system condensed from a cloud of dust and
gases
14. H-R Diagram - a diagram that shows the relationships between a star's
color, its absolute magnitude, and its temperature
15. stars - self luminous bodies of hydrogen and helium
16. nebula - a huge cloud of dust and gases; condense to form stars
17. revolution - the circling of one object about another, the motion of the
planets around the sun and satellites (moons) around the planets
18. meteor - streaks of light produced by a meteoroid as it burns up in
Earth’s atmosphere
19. solar eclipse - occurs when the moon blocks sunlight from Earth’s
surface
20. light year - the distance that light can travel in a year; approximately 6
trillion miles (~ 9 trillion kilometers)
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Part II: Application
1. Explain the relationship between stars, planets, galaxies, moons and the
universe.
Moons revolve around planets, which revolve around stars, which revolve around
the center of a galaxy, which is a typical unit of the universe.
2. Explain what is meant by this statement. "When you look at a star, it might
not actually be there."
Many stars are thousands of light years away. The light we receive from them
takes thousands of years to get to Earth. All stars are in motion so where they
appear to be is actually where they used to be.
3. Explain how Earth's atmosphere became 21% oxygen.
When Earth first formed, its atmosphere did not contain oxygen. One and a half
billion years later life appeared in the oceans. Photosynthesis created oxygen.
4. Use the H-R Diagram to determine the following.
Temperature of the sun.
6,000C
Absolute magnitude of a red giant.
approximately -3
Color of a 4,500C star.
orange
Absolute magnitude of a violet main
sequence star.
approximately -5
Part III: SOL Vocabulary Practice Questions
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1. D
2. D
3. C
4. A
5. D
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