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74 Cards in this Set
- Front
- Back
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How does Earth move?
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through space by rotation and revolution
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axis
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imaginary line that moves through Earth's center & North & South poles
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rotation
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spinning of Earth on it's axis
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revolution
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movement of one object around another
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orbit
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path of an object as it revolved around another object in space
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What is the shape of Earth's orbit?
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ellipse
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Why is it warmer near the equator than the poles?
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cause the sunlight almost directly hits the equator while the poles' sunlight is at steep angles
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What would cause no seasons?
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if the Earth's axis was straight up and down
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How are seasons caused?
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by Earth's axis being tilted as it revolves around the sun
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What are summer and winter caused by?
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Earth's tilt as it revolves around the sun
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What is Earth like in June in the Northern Hemisphere?
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more direct sun rays and more hours; Earth is farthest from the sun
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What is Earth like in June in the Southern Hemisphere?
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less direct sun rays and fewer hours
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What is Earth like in December in the Northern Hemisphere?
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less direct sun rays and fewer hours
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What is Earth like in December in the Southern Hemisphere?
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more direct sun rays and more hours
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Solstices
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when the sun is farthest north or south of the equator; x2 a year
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When is the Northern Hemispheres summer solstice?
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around June 21
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When is the Southern Hemispheres summer solstice?
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around December 21
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When are equinoxes?
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half way between solstice where neither hemisphere is tilted toward the sun; x2 a year
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Equinox
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when the noon sun is directly overhead at the equator
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When is the vernal equinox?
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around March 21 and it marks the start of spring in the North
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When is the autumn equinox?
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around September 21 and it marks the start of fall in the North
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Force
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push or pull
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When did Isaac Newton realize something and what did he realize?
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when an apple fell on his head in 1666 he realized their must be a force acting between the Earth and the Moon to keep the Moon in orbit
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Gravity
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force that attracts all objects toward each other
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Law of Universal Gravitation
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Newton's law that every object in the universe is attracted toward each other
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What does the strength of gravity depend on?
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mass and distance
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Why don't we feel a gravitational pull?
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because the strength of gravity depends partly on mass and we are way less massive than Earth
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Mass
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amount of matter in an object
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Gravity
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force of gravity on an object and can vary depending on location
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Why doesn't the Earth fall into the sun?
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because inertia equally resists the gravitational pull from the sun
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Inertia
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tendency of an object to resist change in motion
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Newton's first law of motion
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object at rest stays at rest and an object in motion stays in motion with a constant speed and direction unless acted on by a force
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What did Newton conclude that kept Earth and the Moon in orbit around the sun?
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inertia and gravity
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What would happen to the Moon if Earth did not have gravity?
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would drift off into space in a straight line
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Why does the Earth revolve around the sun?
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sun's gravity is pulling on the Earth while Earth's inertia moves it ahead
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How does the Moon rotate?
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on axis around Earth
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How long does it take the moon to revolve around the Earth?
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27.3 days
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What causes phases, eclipses, and tides?
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changing relative positions of the moon, Earth, and the sun
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What are three details about the phases of the moon?
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1) 1/2 of the moon is always in the sun
2) see moon from different angles because rotation 3) phase of the moon you see depends on how sunlit side faces Earth |
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How long does it take the phases of the moon to complete it's cycle?
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about 29.5 days after the last new moon
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When do eclipses occur?
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when the moon's shadow hits Earth or Earth's shadow hits the moon
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Phases
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one of different apparent shapes of the moon as seen from Earth
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Eclipses
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partial or total blocking of one object in space from another
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When do solar eclipses occur?
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when the moons passes directly between Earth and the sun blocking sunlight
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Solar eclipse
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blocking of sunlight to Earth that occurs when the moon is directly between the sun and earth
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What are total solar eclipses?
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from any point in the umbra light from the sun is completely blocked (umbra is very small) and the sky grows dark as night and air gets cool and the sky becomes an eerie color
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umbra
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darkest part of shadow
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penumbra
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part of shadow surrounding the darkest part
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When do lunar eclipses occur?
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during the full moon when Earth is directly between the Earth and the sun
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What are total lunar eclipses?
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when the moon is in the umbra you can see a total lunar eclipse anywhere that the moon is visible
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What are partial lunar eclipses?
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when the moon passes partly in the umbra of Earth's shadow. during most lunar eclipses the Earth, moon, and sun are not quite in line, the umbra appears blurry
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What are partial solar eclipses?
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when the penumbra part of the sun is partially visible from Earth. it is not safe to look directly at the sun during a partial solar eclipse
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What are 2 facts about tides?
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-force of gravity pulls the moon and the Earth toward each other
-caused mainly by differences in how much the moon's gravity pulls on different parts of the Earth |
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Tides
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rise and fall of ocean water every 12.5 hours or so
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What is the tide cycle?
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- at any one time 2 places on Earth have high tides and 2 places have low tides
1) as Earth rotates 1 high tide stays on the side facing the moon and the other is in the opposite direction 2) Earth sweeps through 4 tides every 25 hours or so |
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How do spring tides occur?
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when the gravity of the sun and the moon pull in the same direction no matter how the sun, moon, or Earth are lined up
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Spring tide
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tides with the greatest difference between high and low tide when the moon is aligned with Earth at the new and full moon
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When do neap tides occur?
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during 1st and 3rd phases of the moon and the line between Earth and the sun are at right angles. x2 a month
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Neap tides
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tide with least difference between low and high tide that occurs when the moon and sun pull at right angles on each other during the 1st and 3rd quarters of the moon
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How did Galileo make his telescope and what did he see?
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by putting 2 lenses in a wooden tube and he saw the irregular surface of the moon
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What are the features of the moon's surface?
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maria, craters, and highlands
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What did Galileo think maria were?
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oceans but are actually hardened rock formed by lava flows
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maria
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dark, flat areas on the moon's surface formed from huge ancient lava flows
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How did scientists think craters were made and how were they actually made?
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thought they were made by volcanoes but actually made by the impacts of meteoroids.
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Why does Earth not have craters anymore?
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worn away by water, wind, and other forces while no liquid water or atmosphere on the moon so nothing has changed
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Craters
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large round pits on the moon's surface
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meteoroids
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chunks of rock or dust from space
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What was Galileo's mistake with highlands?
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thought light colored features were highlands but what he saw was the shadow of the peaks of lunar highlands. rugged highlands cover most of the moon's surface
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How does the moon compare to Earth?
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The moon is dry and airless, compared to Earth the moon is small and has large variations of temperature
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What is the size and density of the moon?
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- moon = about size of the US
- 1/18 mass as Earth - Earth has a dense core and its outer layers are less dense, the average density of the moon is similar to that of the Earth's outer layers |
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What is the temperature and atmosphere like on the moon?
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-temperature varies since there is no atmosphere
- surface gravity is so weak gases can easily escape |
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What is the mystery of water on the moon?
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-there is no liquid water
- there may be patches of ice near the poles because the temperature in those regions are shielded from sunlight |
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How was the moon formed?
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by the collision theory;
1) planet-sized object crashed into Earth 2) material from outer layers ejected to orbit around Earth forming rings 3) gravity caused material to combine forming the moon |
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What results in the moon revolving around the Earth?
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the moon's orbit is slightly tilted with respect to Earth's orbit around the sun resulting most moths the moon revolves around Earth
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