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closest planet to the sun


rocky planet with water

gas planets

outer planets (Jupiter, Saturn, Uranus, Neptune)

rocky planets

inner planets (Mercury, Venus, Earth, Mars)


force that keeps the planets in motion around the sun


satellite that revolves around a planet




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


caused by the tilt of the Earth





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


Earth considered the center of the universe


had a geocentric model of the solar system


thought movement of planets and stars was circular


the sun is the center of the solar system


heliocentric model of solar system, Earth rotates on its axis


was imprisoned for proving the heliocentric model

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