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What is 1 + 3?
The study of the moon, stars, and other objects in space.
The movement of an object around another object.
The two days of the year on which the sun reaches its greatest distance north or south of the equator.
An imaginary line that passes through earth's center and the north and south poles, about which earth rotates.
The path of an object as it revolves around another object in space.
The two days of the year on which neither hemisphere is tilted toward or away from the sun.
The spinning motion of a planet on its axis.
A system of organizing time that defines the beginning length and divisions of a year.
A push or pull exerted on an object.
The attractive force between objects its strength depends on their masses and the distance between them.
Law of universal gravitation
The scientific law that states that every object in the universe attracts every other object.
The amount of matter in an object.
The force of gravity on an object.
The tendency of an object to resist a change in motion.
Newton's first law of motion
The scientific law that states that an object at rest will stay at rest and an object in motion will stay in motion with a constant speed and direction unless acted on by a force.
One of the different apparent shapes of the moon as seen from Earth.
The partial or total blocking of one object in space by another.
The blocking of sunlight of earth that occurs when the moon is directly between the sun and earth.
The darkest part of a shadow.
The part of a shadow surrounding the darkest part.
The blocking of sunlight to the moon that occurs when the earth is directly between the sun and the moon.
The periodic rise and fall of the level of water in the ocean.
The tide with the greatest difference between consecutive low and high tides.
The tide with the least difference between consecutive low and high tides.