Earth, Moon, and Sun
by Cali Karbler
Chapter 1 sections 1-4 Key concept questions
Section 1-Earth in Space
How does Earth move in space?
Earth moves in space in two major ways, rotation and revolution.
Rotation is the spinning of earth on it's axis. The axis is the imagery line that passes through Earth's center of its North and South poles. Rotation causes day and night, one rotation is called a day. One rotation takes 24 hours.
Revolution is the movement of Earth moving around the sun. One complete revolution is called a year. Earth follows an orbit, which is the path it takes around the sun. Earth's orbit isn't circular, it's slightly ellipse. There are about 365 days in a year, but because it's not exactly 365 days in a year, every 4 years we add an extra day called a leap year.
What causes the cycle of seasons on Earth?
Earth has seasons because its axis is tilted as it revolves around the sun.
When Earths axis are straight sun light is mostly evenly distributed, so there would be no seasons. When the northern hemisphere is faced mostly toward the sun the season is summer. When the southern hemisphere is faced toward the sun, the northern hemisphere is having winter.
Section 2-Gravity and Motion
What determines the strength of the force of gravity between two objects?
The force of gravity between two objects depends on the masses of the object and the distance between them.
Mass is the amount of matter in an object. Earth is so massive, it exerts a great amount of gravitational pull. Its such an extreme amount of force it is able to keep the moon in orbit.
The force of gravity decreases rapidly as the distance increases. If the distance of two objects doubled, the gravity between them would decrease 1/4 of its original value.
What two factors combine to keep the moon and Earth in orbit?
Newton said that inertia and gravity combine to keep the moon in orbit around the Earth.
Inertia is the tendency of an object the resist a change.
Gravity is the attractive force force between two objects.
Earth's gravity keeps pulling the moon toward it, preventing the moon from going in a straight line. At the same time, the moon keeps moving ahead because of its inertia . If not for Earth's gravity the moon would move throughout space in a straight line.
Section 3-Phases, Eclipses, and Tides
What causes the phases of the moon?
The phases of the moon you see depend on how much of the sunlight side of the moon faces toward Earth.
The different shapes of the moon you see from Earth are called phases.
The moon goes through a whole set of phases as it makes a complete revolution around Earth. Phases are caused by the different changes in the relative positions of the moon, Earth and sun. The sun lights the moon, haft the moon is always light up. Since the moon revoles around Earth, you see the moon from different angles.
What are solar and lunar eclipse?
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.
During a lunar eclipse, Earth blocks sunlight from reaching the moon.
What causes the tides?
Tides are cause by differences in how much the moon's gravity pulls on different parts of Earth.
Tides are the rise and fall of ocean water that occurs every 12.5 hours. The water rises for about 6 hours, and falls around 6 hours on a regular cycle.
Section 4-Earth's Moon
What features are found on the moon's surface?
Features on the moon include maria, craters, and highlands. Galileo mistakes for seas.
Maria means seas in Latin. The moon surfaces have dark flat areas which Galileo mistakes for seas. They are actually harden rock formed from huge lava flows that occurred between 3-4 billion years ago.
Galileo saw that the moon's surface was marked by large pits called craters. Craters are created by the impact of meteor ids, chunks of rocks or dust from space.
Galileo correctly inferred that some of the light colored features on the moon were highlands. The peaks of the lunar highlands and the rims of the craters cast dark shadows, which Galileo could see. The rugged lunar highlands cover a lot of moon's surface.
What are some characteristics of the moon?
The moon is dry and airless. compared to the Earth, the moon is small and has large variations in its surface temperature.
The moon is 3,476 kilometers in diameter. This is around 1/4 of Earth's diameter.
On moon's surface temperatures range from 130 degrees, to -180 degrees. These temperatures vary so much because the moon has no atmosphere.
How did the moon form?
They are many theories of how the moon was formed.
The best fit origin of the moon is called collision-ring theory. About 4.5 billion years ago the solar system was full of rocky debris. Scientists believe that a planet sized object collide with Earth and created the moon. Material from the object and Earth's outer layers was ejected int orbit around Earth, were it formed a ring. gravity caused this material to combine and from the moon.