The Earth, Moon, and Sun
By: Alex Akers
Where I tracked the moon from
Moon observation Sheet
Section 1, Earth in Space
How does the Earth move in space?
The Earth moves by both rotating and revolving in space.
There is an imaginary line that passes through Earth's surface through the poles. This line is called its axis. The Earth spins on the axis, or rotates.
The Earth Also revolves around the Sun. The Earth travels in this path, called its orbit, around the sun and every revolution is one year.
What causes the causes the cycle of seasons on Earth?
The earth is tilted on its axis at an angle of 23.5 degrees. Because of this, as the Earth revolves around the sun, certain parts of the Earth get more sunlight than others. For example, when it is Summer in the Northern Hemisphere, the Northern Hemisphere gets more direct sunlight than the Southern Hemisphere at this time of year.
Section 2, Gravity and Motion
What determines the strength of the force of gravity between 2 objects?
The strength of the force of gravity depends on 2 factors: the masses of the objects attracted and the distance between them.
Mass is the amount of matter in an object. If the mass of the object is less than the object it is attracted to, it will exert less force or gravity than that other object; and vice versa. For example, the Earth has a much greater mass than the moon, so it exerts a greater amount of gravitational force, keeping the moon in its orbit and not the other way around.
The force of gravity also depends on the distance between 2 objects. The greater the distance, the smaller the force of gravity. The lesser the distance, the greater the force of gravity. For example, if the distance between 2 objects attracted to each other doubled, the the force of the gravity would only be one fourth of what it originally was.
What 2 factors combine to keep the moon and the Earth in orbit?
Inertia and gravity combined keep the Earth and moon in orbit with each other and the sun.
Inertia is the tendency of an object to resist change in motion. Without gravity pulling the moon towards the Earth or the Earth towards to sun, inertia would have either object travel in a straight line out of orbit, not the elliptical motion that they currently do.
Gravity is the force that attracts all objects toward each other. Gravity forces the moon not to stray from the Earth, and the Earth not to move away from the sun. But inertia keeps any of the objects from colliding together because inertia is trying to force the moon/earth to move in a straight line, while the combined efforts create an elliptical orbit around the earth/sun.
Phases, Eclipses, and Tides
What causes the phases of the Moon?
The phases are the different shapes of the moon you see from Earth.
Phases are caused by the changes in relative positions between the Earth, Moon, and sun. The moon doesn't actually emit its own light, just reflects light from the sun. So, the phase of the moon that is seen depends on how much of the sunlit side is facing Earth.
What are solar and lunar eclipses?
A solar eclipse occurs when the moon passes directly in front of the sun, blocking the sunlight from earth. The moon's shadow then hits the Earth, causing a solar eclipse. To be able to experience a total solar eclipse only people in the umbra, or moon's cone shaped shadow that falls on Earth. To be in the tip of that shadow would mean that it is completely dark outside, the air gets cooler, and you can even see the stars. To experience a partial solar eclipse, a person would have to be in the penumbra, or the larger part of the moon's shadow where they could see part of the sun.
A lunar eclipse occurs when the Earth is directly between the moon and the sun, so that the Earth's shadow falls over the moon. Lunar eclipses can only happen when there is a full moon because that is when the moon is closest to the Earth. Just like for a solar eclipse, to experience a total lunar eclipse, the moon has to be entirely in the Earth's umbra. Although, a total lunar eclipse can be seen from anywhere on Earth that the moon is visible. A partial lunar eclipse occurs when the moon is only partially in the Earth's umbra.
What causes the tides?
Although the moon is in the Earth's orbit, the moon still has some gravitational force on Earth, such has controlling the water or tides. The tides occur because of how much the moon's gravity pulls on different parts of Earth.
What features are found on the Moon's surface?
There are maria, craters, and highlands on the moon's surface.
The dark, flat areas on the moon are called maria, which means seas in Latin. Galileo thought that maria were oceans, but he was wrong. They are actually hardened rock formed from lava that occurred between 3 and 4 billion years ago.
There are large round pits called craters on the moon's surface too. Craters can be hundred kilometers across, too. Scientists used to think that craters formed because of volcanoes, but eventually figured out that they were caused by impacts from meteoroids. Earth used to have craters like the moon, but they eventually got worn away.
Galileo also correctly believed that some of the lighter colored areas on the surface of the moon were highlands, or mountains. The highlands and rims of craters cast shadows, which Galileo could see. Highlands cover much of the moon's surface.
What are some characteristics of the moon?
Although the moon is only 384,000 kilometers from Earth and is closest to Earth, the moon is very different.The moon is dry and doesn't have air, it is also very small and cold compared to Earth. To be able to survive on the moon people must wear a bulky space suit that is able to provide oxygen, protect you against the sun, and keep you at a comfortable temperature.
The moon is 3476 kilometers across or about one-fourth of Earth's diameter. But, the moon is still only one-eightieth of the Earth's mass. The average density of the moon is about the same as that of Earth's outer layers. The temperature of the moon ranges from 130-negative 180 degrees Celsius because the moon doesn't have an atmosphere; the there is a wide range of temperatures. Although the moon doesn't have any liquid water, there is evidence that there may be large patches of ice near the poles.
How did the moon form?
There are many theories about how the moon formed. The collision-ring theory seems the most plausible theory as of right now. The theory states that about 4.5 billion years ago our solar system. Scientists believe that a planet-sized object collided with Earth. Objects from the Earth's outer layers dispersed, creating a ring around Earth. Finally, gravity caused this material to form the moon.