Earth, Moon, and Sun
By Isabelle Seewald
My Observation Center (KMS)
Section 1-Earth in Space
How does the Earth move in Space?
Earth moves in space in 2 different ways.
One way is rotation. The earth spins on its axis. That's the imaginary line that passes through Earth's center and the North and South Poles.
Another way Earth moves in Space is revolution. During revolution, the sun rotates around the sun. To do so, the Earth follows its orbit.
What Causes the Cycle of Seasons on Earth?
The cycle of seasons on Earth is caused by the tilt of Earth's axis as it revolves around the sun.
In June, the northern hemisphere is warmer than the southern hemisphere because the north end of the axis is pointed toward the sun.
In December, the southern hemisphere is warmer than the northern hemisphere because the south end of the axis is pointed toward the sun.
In March and September, neither end is pointed toward the sun, so each hemisphere receives the same amount of sun.
Section 2-Gravity and Motion
What determines the strength of the force of gravity between two objects?
The strength of gravity is affected by the distance between two objects and their masses, which is also known as Newton's law of Universal Gravitation. That states that every object in the universe attracts every other object.
What two factors combine to keep the Earth and moon in orbit?
The two factors that keep the moon and Earth in orbit are inertia and gravity.
Inertia is the tendency of an object to resist a change in motion. Earth's gravity keeps pulling the moon toward it, which prevents the moon from moving in a straight line. But at the same time, the moon moves ahead because of its inertia.
Earth's gravity helps create the inertia, keeping the moon from going off into space.
Section 3-Phases, Eclipses, and Tides
What causes the phases of the moon?
The phases are caused by changes in the relative positions of the moon, Earth, and the sun. The sun is what lights the moon, and that's what we see, also known as the phases of the moon. The phase of the moon you see depends on how much sunlight is hitting the side of the moon that faces Earth. When all of the phases have been shown, that is one revolution around Earth.
What are Solar and Lunar Eclipses?
When the moon's shadow hits Earth or Earth's shadow hits the moon, an eclipse occurs.
A solar eclipse occurs when the moon passes directly between Earth and the sun, blocking sunlight from Earth.
A lunar eclipse occurs at a full moon when Earth is directly between the moon and the sun.
What causes the Tides?
Tides are caused mainly by differences in how much the moon's gravity pulls on different parts of the Earth.
In a spring tide, the gravity of the sun and moon pull in the same direction which produce a tide with the greatest difference between consecutive low and high tides, known as a spring tide.
In a Neap Tide the line between Earth and the sun is at right angles to the line between Earth and the moon, which creates a neap tide.
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.
The dark, flat areas on the moon's surface are called maria, which is Latin for "seas". Maria is hardened rock formed from huge lava flows.
The large round pits on the moon's surface are called craters. They were caused by chunks of rocks known as meteoroids. They were formed before the maria were.
What are Some Characteristics of the Moon?
The moon is dry and airless. Compared to Earth, the moon is small and has large variations in its surface temperature.
The moon is 3,476 kilometers in diameter. It has only 1/80 as much mass as Earth. The moon's average density is similar to the density of Earth's outer layers.
The moon's surface temperature ranges from about -180 degrees Celsius to about 130 degrees Celsius. It varies because the moon has no atmosphere. It's gravity is very weak, so gases can easily escape into space.
The moon has no liquid water, but there is evidence that shows there are patches of ice near the moon's poles. In some areas on the moon, the sunlight is blocked off by crater walls, so the ice patches would remain frozen there.
How did the Moon form?
Scientists have suggested many possible theories. Was the moon formed somewhere else in the solar system and captured by Earth's gravity? Was the moon formed near Earth at the same time that Earth formed? At the same time, scientists have found reasons to reject these ideas. The best fit theory is called the collision-ring theory. Scientist say that a planet-sized object collided with Earth to form the moon. Material from the object and Earth's outer layer escaped into orbit around the Earth, and gravity caused it to combine, creating the moon.