Earth, Moon, and Sun
Earth In Space
How does Earth move in space?
Earth moves through space by revolution and rotation. Revolution is the movement of one object around another. When the Earth makes a full revolution around the sun it takes 365.25 days and is known as a year. Rotation is the spinning of Earth on it's axis. The rotation causes day and night and a full rotation is a day.
What causes the cycle of seasons on Earth?
If Earth Didn't have a tilted axis, there would be no seasons. When the North end of the axis is pointing towards the sun, it is summer in the Northern Hemisphere and Winter in the Southern Hemisphere. When the North end of the axis is pointed away from the sun, it is summer in the Southern Hemisphere and winter in the Northern Hemisphere. When the North end of the axis is neither pointing towards or away from the sun, both Hemispheres receive the same amount of sun and it is either fall or spring.
This video shows rotation, revolution, and the seasons of Earth.
What determines the strength of the force of gravity between two objects?
The strength of the force of gravity between two objects depends on the masses of the objects and the distance between them. If the mass increases of the objects, then the force of gravity between the two objects will increase. If the mass decreases, the the force of gravity between the two objects will decrease. If the distance between two objects increases, then the force of gravity between the two objects will decrease. If the distance between two objects decreases, then the force of gravity between the two objects will increase.
What two factors combine to keep the moon in orbit?
Inertia and gravity combine to keep the moon in orbit. Inertia is the tendency of an object to resist change in motion. Gravity is a force that attracts all objects toward each other. Inertia+gravity doesn't only keep the moon in orbit around the Earth, it also keeps the Earth in orbit around the sun.
This is a video that shows a couple demonstrations of inertia.
What causes the phases of the moon?
Like the Earth, the moon rotates on an axis and revolves around the Earth. As the moon revolves around the Earth, the relative positions of the sun, moon, and Earth change; these changes cause the phases of the moon, eclipses, and tides. The moon goes through all of its phases each time it makes a full revolution around Earth. The phase you see depends on how much of the bright side of the moon faces Earth.
What are solar and lunar eclipses?
An eclipse happens when the moons shadow hits the Earth or the Earths shadow hits the moon. A solar eclipse happens when the moon passes directly between Earth and the sun and blocks the sunlight from hitting the Earth; this occurs with a new moon. A lunar eclipse occurs when Earth blocks sunlight from reaching the moon; this occurs with a full moon.
What causes the tides?
The Earth and the moon are pulled towards each other by the force of gravity. The tides are caused by differences in how much the moons gravity pulls on different parts of Earth.
What features are found on the moons surface?
On the moon there are maria, craters, and highlands. The maria are dark flat areas of the moon; Galileo thought they were oceans so he called them maria which means seas. Craters are large round pits in the moons surface. The craters were caused by meteoroids. Highlands are mountains and they cover much of the moons surface.
What are some characteristics of the moon?
The moon has no air and is very dry. The moon is small in size compared to Earth and has large variations of temperature. The moon is 3,476 kilometers in diameter and has about one-eighteenth as much mass as the Earth. The temperature on the moon varies from 130 degrees C to -180 degrees C because the moon does not have and atmosphere. The moon has no water but scientists believe that there might be some ice near the poles.
How did the moon form?
Nobody knows for sure how the moon formed but scientists believe that a planet sized object collided with Earth and formed the moon. The collision caused a ring of rubble to surround Earth. Gravity caused the material in the ring to combine and the moon was formed.