Earth, Moon, and Sun
By: Sarah Soryal
Section 1: Earth in Space
How does Earth move in Space?
Earth moves through space in two major ways: rotation and revolution. The invisible line that goes through the Earth's southern and northern poles is called the Earth's axis. When the Earth spins on it's axis it is called rotation. The Earth's rotation causes day and night since it takes 24 hours for the Earth to make a full rotation. Revolution is the movement of one object around another. The Earth revolves around the sun.
What causes the cycle of seasons on Earth?
The tilt of the Earth's axis as it revolves around the sun causes seasons. As the Earth revolves around the sun, one half of the Earth is always tilted towards the sun (either the northern hemisphere or the southern hemisphere). The hemisphere that is tilted towards the sun at a specific time experiences summer (since the sun's rays are more direct there) while the other hemisphere tilted away from the sun is experiencing winter (since the sun's rays are more spread out and indirect there).
Section 2: Gravity and Motion
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 objects' masses increase the force also increases. This is because objects with greater masses exert a greater force. If the distance increases however, the force decreases. This is because the gravitational pull between objects weakens with increasing distance.
What two factors combine to keep the moon and Earth in orbit?
Inertia and gravity combine to keep the moon and Earth in orbit. The Earth's gravity pulls the moon towards it which doesn't allow the moon to move in a straight line so the moon is forced to circle the Earth. Inertia is the tendency of an object to resist a change in motion. The moon's inertia is what keeps the moon moving forward around the Earth.
Section 3: Phases, Eclipses, and Tides
What causes the phases of the moon?
The ever changing locations of the moon, Earth, and sun causes the phases of the moon. Since the moon is lit by the sun, the backside of the moon is always facing the sun. However, the moon revolves around Earth so the angles in which we see the sunlight on the moon is constantly changing, causing us to view the moon's phases.
What are solar and lunar eclipses?
When the moon's shadow hits Earth or Earth's shadow hits the moon, an eclipse occurs. The two types of eclipses are solar eclipses (named after the Latin word for sun), and lunar eclipses (named after the Latin word for moon). A solar eclipse occurs when the moon passes directly between Earth and the sun, blocking sunlight from Earth. A lunar eclipse occurs when Earth blocks sunlight from reaching the moon.
What causes the tides?
Tides are caused mainly by differences in how much the moon's gravity pulls on different parts of Earth. As the moon revolves around Earth, different parts of Earth are closer to the moon at a specific time. These closer parts experience high tide (larger waves) since the moon is closer, therefore the moon's gravity pulls at Earth (specifically water) more causing the tides to rise. While there is high tides at one part of Earth, the other side of Earth experiences low tide since the pull of gravity is not as strong.
Section 4: Earth's Moon
What features are found on the moon's surface?
Features on the moon's surface include maria, craters, and highlands. Maria is the Latin word for seas. The maria on the moon are hardened rock formed from lava flows that occurred 3 and 4 billion years ago. Craters are large round pits. The moon's craters were formed from meteors hitting the moon and some are kilometers across. Highlands are mountains or peaks on the moon.
What are some characteristics of the moon?
The most noticeable characteristics of the moon is it's lack of air, its small size (in comparison to Earth), and it's large variations in its surface temperature. The moon doesn't have an atmosphere, so it isn't able too keep in air. The moon is 3,476 kilometers in diameter which is only a little smaller than the distance across the United States. The moon's temperatures range from 130 degrees Celsius in direct sunlight to -180 degrees Celsius.
How did the moon form?
Scientists theorize that a planet-sized object collided with Earth to form the moon. Parts of the object (whatever the planet-sized object was) and the outer layers of Earth were broken off and went into orbit around Earth. Gravity pulled these pieces together to form the moon.