Astronomy Review 18-19

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Terms in this set (...)

heliocentric
sun-centered model of the universe
geocentric
earth-centered model of the universe
ellipse
oval orbit
comet
a ball of ice and dust that becomes lit as it travels close to the sun
constellation
a group of stars that is imagined to look like a picture of a person, thing, or animal
star
a large ball of burning gas in space mostly composed of oxygen and helium
planet
an object in space that orbits a star, is large enough to have become rounded by its own gravity, and has cleared the area (neighborhood) of its orbit
meteor
a streak of light in the sky produced by the burning of a meteoroid in Earth's atmosphere
satellite
an object that orbits a planet
inertia
an object at rest will stay at rest, and an object in motion will stay in motion
gravity
A force that pulls objects toward each other
weight
A measure of the force of gravity on an object
equinox
Each of the two times of the year when days and nights are of equal length
solstice
Time when the Sun is farthest from the equator.
universe
All of space and everything in it (planets, stars & galaxies)
orbit
The path of an object as it revolves around another object in space
rotation
the spinning motion of a planet on its axis
axis
an imaginary line that passes through the poles of a planet and its center
revolution
The movement of an object around another object
umbra
the darkest part of a shadow
penumbra
The part of a shadow surrounding the darkest part
lunar eclipse
an eclipse that occurs when the Earth passes between the sun and the moon.
solar eclipse
an eclipse that occurs when the moon passes between the sun and Earth, making the sun appear dark.
neap tide
the tide with the least difference between low and high tide; has low high tides and high low tides.
spring tide
the tide with the greatest difference between high and low tides has high high tides, low low tides.
phase
one of the different shapes of the moon as seen from Earth.
waxing
the lit portion is getting larger
waning
becoming less bright, intense, or strong
stars
there are billions in our galaxy & their light takes millions of light-years to reach us
light-year
the distance light can travel in a year; used to measure light from stars
Date of Winter Solstice
December 21st
Date of Summer Solstice
June 21st
Milky Way
the name of our galaxy, a spiral galaxy that contains about 400 billion stars
Day (24 hours)
the time required for Earth to rotate once on its axis
Month (29-31 days)
the time it takes for the moon to rotate around the Earth once
Year (365 days)
The time it takes the Earth to go around the sun once
Sunlight on earth during Summer Solstice (Northern Hemisphere)
Northern Hemisphere is tilted towards the sun (direct sunlight)
Sunlight on Earth during Winter Solstice (Northern Hemisphere)
Northern hemisphere is tilted away from the sun (indirect sunlight)
Nicolaus Copernicus
Devised a model of the universe with the Sun at the center, and not earth. (heliocentric model)
Claudius Ptolemy
He believed that the Earth was at the center of the Universe, and that the sun and other planets revolved around the Earth. (geocentric model)

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