41 terms

Earth, Moon, and Sun

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astronomy
the study of the moon, stars and other objects in space
rotation
the spinning motion of a planet on its axis, causes day and night
axis
an imaginary line that passes through Earth's center and the North and South poles, about which Earth rotates, causes seasons
revolution
the movement of an object around another object
orbit
the path of an object as it revolves around another object in space
equinox
the two days of the year on which neither hemisphere is tilted toward or away from the sun
solstice
the two days of the year on which the sun reaches its greatest distance North or South of the equator
force
a push or pull exerted on an object
gravity
the attractive force between objects; its strength depends on their masses and the distance between them
inertia
the tendency of an object to resist a change in motion
phase
one of the different apparent shapes of the moon as seen from Earth
eclipse
the partial or total blocking of one object in space by another
umbra
the darkest part of a shadow
penumbra
the part of a shadow surrounding the darkest part
tide
the periodic rise and fall of the level of water in the ocean
solar eclipse
the blocking of sunlight to Earth that occurs when the moon is directly between the sun and the earth
lunar eclipse
the blocking of sunlight to the moon that occurs when the earth is directly between the sun and the moon
spring tide
the tide with the greatest difference between consecutive low and high tides
neap tide
the tide with the least difference between consecutive low and high tides
telescope
a device built to observe distant objects by making them appear closer
Maria
dark, flat areas on the moon's surface formed from huge ancient lava flows
crater
a large round pit caused by the impact of a meteoroid
meteoroid
a chunk of rock or dust in space
How does earth move in space?
it rotates around its axis as it revolves around the sun
What causes the cycle of seasons on Earth?
the 23.5 degree tilt of Earth's axis as it revolves around the sun causes its seasons
leap year
when one day is added every four years to fit the 365 1/4 day revolution around the sun
When is Earth farthest from the sun?
though Earth is tilted toward the sun during summer in the northern hemisphere, it is farthest away from the sun
How would the seasons be different if Earth were not tilted on its axis?
Earth would have the same season in both hemispheres year-round if it were not tilted on its axis because both hemispheres would receive equal sunlight
law of universal gravitation
every object in the universe attracts every other object
what two factors act together to keep Earth in orbit around the sun?
gravity and inertia
Why doesn't Earth simply fall in to the sun?
the Earth has too much inertia for it to fall into the sun, it's very strongly resisting a change in motion, and that change in motion would be falling into the sun
During which phase of the moon can lunar eclipses occur?
lunar eclipses can occur at full moons
What causes the moon to shine?
reflected light from the sun causes the moon to shine
Why does the moon appear to change shape in the course of a month?
you see more or less of the sunlit side of the moon in the course of a month
Why isn't there a solar eclipse and a lunar eclipse each month?
the earth, moon, and sun don't line up perfectly every month
What causes tides?
tides are caused by the differences in how much the moon's gravity pulls on different parts of Earth
What theory best explains the moon's origin?
the collision-ring theory: a planet sized object collided with Earth, material from the object and Earth was ejected into orbit around Earth, forming a ring, gravity brought this material together into the moon
three major features of the moon's surface
maria, craters, highlands
How did the moon's craters form?
the moon's craters were made by the impact of meteoroids
why is the moon's surface much more heavily cratered than Earth's surface?
the moon has no weather to even out it's surface
What was the solar system like when the moon formed?
the solar system when the moon formed was filled with rocky debris, some of which the size of small planets