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Aidin
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Celestial object
any object that exists in space, such as a planet, a star, or a moon
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astronomer
a scientist who studies astronomy
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revolution
the time it takes for an object to orbit another object; Earth's revolution around the sun is 365.24 days
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rotation
the turning of an object around an imaginary axis running through it; Earths rotation around its axis is 24 hours
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constellation
a group of stars that seem to form a distinctive pattern in the sky
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light-year
the distance that light travels in one year, about 9.5 X 10 to the power of 12 km
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apparent magnitude
the brightness of a star as seen from earth
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asterism
a smaller group of stars that form a pattern inside of a constellation
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pointer stars
The pointer stars are the two end stars of the plough, they are referred to as the 'pointer' because they show the way to the Pole Star or Polaris which is the main star in the Ursa Minor constellation. All of the stars seen in the night sky emerge to revolve around the Pole Star.
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circumpolar
A circumpolar star is a star that, as viewed from a given latitude on Earth, never sets (that is, never disappears below the horizon), due to its proximity to one of the celestial poles
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zenith
The zenith is an imaginary point directly "above" a particular location, on the imaginary celestial sphere
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tides
the rising and falling of ocean waters caused by the moon's and earth's gravity
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phases of the moon
the monthly progression of the changes in the appearance of the moon that result from different portions of the moon's sunlit side being visible from other
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lunar eclipse
the phenomenon in which the full moon passes into earth's shadow
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solar eclipse
the phenomenon in which the shadow of the moon falls onto earth's surface
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why do we have seasons?
We have seasons because the earth is tilted (wonky) as it makes its yearly journey around the sun.
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planet
an object that orbits one or more stars (and is not a star itself), is spherical, and does not share its orbit with another object
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retrograde motion
the movement of an object in the sky, usually a planet, from east to west, rather than its normal motion from west to east; this effect is generally produced when earth is passing the planet in its orbit
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astronomical unit
the average distance between the earth and the sun, about 150 X 10 to the power of 6 km
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orbital radius
the average distance between the sun and and object that is orbiting the sun
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geocentric model
a model of the solar system stating that the earth is the center of all planetary motion, with the planets and sun travelling in perfect circles around the earth
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heliocentric model
a model of the solar system in which the sun is in the center of the planets orbiting it
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comet
an object composed of rocky materials, ice and gases; comes from the kuiper belt and oort cloud
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asteroid
an object in space that ranges in size from a tiny speck, like a grain of sand, to 500 km wide; most asteroids originate in the asteroid belt between mars and Jupiter
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meteoroid
a piece of rock moving through space
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meteor
a meteoroid that hits earth's atmosphere and burns up
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meteorite
a meteorite that is large enough to pass through earth's atmosphere and reach the ground without totally being burned up
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Trans-Neptunian object
an object that circles the sun beyond the orbit of Neptune
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