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Mercury

closest planet to the sun

Earth

rocky planet with water

gas planets

outer planets (Jupiter, Saturn, Uranus, Neptune)

rocky planets

inner planets (Mercury, Venus, Earth, Mars)

gravity

force that keeps the planets in motion around the sun

moon

satellite that revolves around a planet

rotate

spin

revolve

move in a circular motion around another object

dwarf planet

small body that revolves around the sun but cannot move other objects away from its orbital neighborhood

day and night

caused by Earth's rotation

seasons

caused by the tilt of the Earth

waxing

growing

waning

shrinking

waxing crescent

lit up crescent on the right

1st quarter moon

lit up on the right half of the moon that we can see.

waxing gibbous

almost all of the moon is lit up from the right to the left, except a small bit on the left.

full moon

a phase of the moon where all of the moon that we can see is lit up and visible.

waning gibbous

all of the moon is lit up except for a small bit on the right side of the moon that we can see.

third quarter moon

left half of the moon that we can see is lit up.

waning crescent

only the left sliver of the moon is visible and has a crescent shape

new moon

no visible moon because the sun shines only on the side facing away from earth

solar eclipse

when the moon blocks the sun

lunar eclipse

when the earth casts a shadow on the moon

4.5 billion years

approximate age of Earth

geocentric

Earth considered the center of the universe

Ptolemy

had a geocentric model of the solar system

Aristotle

thought movement of planets and stars was circular

heliocentric

the sun is the center of the solar system

Copernicus

heliocentric model of solar system, Earth rotates on its axis

Galileo

was imprisoned for proving the heliocentric model

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