Other than planets, name three things that orbit the sun.
Dwarf planets, comets, and dust.
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Approximately how old is the Solar System?
5 thousand million years old.
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What is the source of the sun's energy?
The fusion of hydrogen nuclei.
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What are comets made of?
Rock, dust, and ice.
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Roughly how many stars make up the milky way?
Thousands of millions.
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What is a light year?
The distance that light travels in a vacuum (like space) in one year.
7 of 22
Briefly describe parallax and how it's used to measure the distance of nearby stars.
When something appears to move when you look at it from different places. Astronomers take photos of the sky six months apart and then observe the apparent movement. The bigger the movement the closer the star is.
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Explain why we see stars and galaxies as they were in the past.
Light travels at a certain speed, so the further away something is in space, the longer the light takes to get to us.
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What is red shift?
When a galaxy is moving away from us and the wavelength of the light from it changes, this causes the light to become redder.
10 of 22
Explain the evidence that shows that the universe is expanding.
Red shift can be seen, and we know that red shift occurs when objects in space are moving away.
11 of 22
Name the process that wears mountains down.
Erosion.
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Briefly explain Wegener's theory of continental drift.
About 300 million years ago there had been ONE continent (Pangaea) and over time it broke up into smaller chunks and spread out.
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Give three reasons why Wegener's theory was rejected at first.
His theory couldn't explain things that the 'land bridge' theory could, his explanation of how the 'drifting' happened wasn't convincing, and he was a meteorologist (not a geologist).
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How fast are some sea floors spreading each year?
By a few CENTIMETERS per year.
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Briefly explain the changes you see in the magnetic orientation of sea floor rocks.
When the Earths magnetic orientation changes the alignment of the rocks change with it.
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What causes tectonic plates to drift?
Convection currents.
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Where do most earthquakes and volcanoes occur?
Near the edges of the plates.
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How are the Himalayas being formed?
By India crashing into the Eurasian plate.
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Name the two types of seismic waves caused by earthquakes, and state whether each type is a transverse or longitudinal wave.
P-Waves= longitudinal, and S-Waves=transverse.
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What type of seismic wave cannot pass through liquids?
S-Waves.
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What is the formula that relates wave speed, frequency, and wavelength?
Speed= Frequency x Wavelength
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Other cards in this set
Card 2
Front
Other than planets, name three things that orbit the sun.
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