Earth, Moon, and Sun
by: Laura Parsons
Key Concepts-section 1:
#1 How does the Earth move in space?
There are two major ways the Earth moves through space, and those are rotation and revolution.
The Earth rotates on an axis around the sun. This rotating causes night and day in different hemispheres. The Earth also follows an orbit. This means that as the earth is rotating, it is also following a path around the sun.
#2 What causes the cycle of the seasons?
The cycle of the seasons are caused by the tilted axis of the Earth. As the Earth orbits around the sun, there are points where it will be tilted away from the sun or facing toward it. When a hemisphere is tilted toward the sun it will receive more sunlight. When this happening you get a warm season like spring or summer. The Earth will keep orbiting and soon that same hemisphere will tilt away from the sun. This is when you get a cold season like fall or winter due to less direct sunlight.
Whatever season it is in one hemisphere, it is the opposite in the other.
#3 What determines the strength of the force of gravity between two objects?
The strength of the force of gravity between two objects is determined by the masses of the objects and the distance between them. The more mass an object has, the stronger the pull of gravity will be; the greater distance between the objects, the weaker the pull will be.
#4 What two factors combine to keep the moon and Earth in orbit?
Inertia and gravity keep the moon and earth in orbit. Earth's gravity pulls the moon toward it, but the moon keeps moving ahead because of its inertia. Without the Earth's gravity, inertia would cause the moon to keep moving through space in a straight line.
Inertia is the tendency of an object to resist a change in motion.
The Earth is in orbit due to the gravity of the sun just like how the moon is in orbit because of the Earth's gravity.
#5 What causes the phases of the moon?
The phases of the moon depends on how much of the sunlight side of the moon faces the Earth.
The moon reflects light from the sun-this is the side of the moon we can see. However, the angle from which we see the moon changes as the moon orbits around the Earth. This is why we end up seeing more or less of it. The result of all of this are the phases of the moon
#6 What are the solar and lunar eclipses?
An solar and lunar eclipse happens when the moon's shadow hits Earth or Earth's shadow hits the moon. An eclipse must have an object come between the sun and a third object.
With a solar eclipse, the moon passes between the Earth and the sun blocking sunlight from reaching the Earth. However, only in the umbra (the moon's darkest shadow) is all light completely blocked and temperatures drop. Everywhere else is still in the Earth's shadow but there is still sunlight. This area is called the penumbra.
A lunar eclipse happens when the Earth passes directly between the sun and the moon. During this eclipse, the Earth is blocking sunlight from reaching the moon. There is also an umbra and penumbra with a lunar eclipse. This can only happen during a full moon because the moon is closest to the Earth's shadow at that time.
#7 What causes the tides?
Tides are caused by differences in how much the moon's (and also the sun's) gravity pulls on different parts of the Earth. Depending on where the moon is in relationship to the Earth, the gravity will be stronger on the tides causing them to rise(high tide) or be weaker and the tides will fall(low tide).
The sun's gravity can also pull on the Earth's waters and a spring tide or neap tide can occur.
Tides are the rise and fall of ocean water that occurs about every 12.5 hours. The water rises and falls in a regular schedule of about 6 hours for each rise and fall.
#8 What features are found on the moon's surface?
Features found on the moon's surface include maria, craters, and highlands.
Maria is the word used for the dark, flat areas on the moon's surface. The maria are hardened rock formed from huge lava flows that occurred billions of years ago from volcanoes on the moon.
Craters are large round pits that mark the Earth's surface. They are made from the impacts of meteoroids (chunks of rocks and dust). Most of the craters were formed before the maria and have stayed almost exactly the same for all those billions of years.
Highlands are the mountains of the moon. They were seen by Galileo as dark shadows and light areas caused by the peaks of mountains and edges of craters. Highlands cover most of the moon.
#9 What are some characteristics of the moon?
Some characteristics of the moon are its size and density, temperature and atmosphere, as well as water.
The size of the moon's diameter is about only one-fourth of the Earths. The mass of the moon is only one-eightieth the Earth's mass. The moon's density is similar to Earth's less dense outer layers. Temperature on the moon's surface can be as hot as 130 degree Celsius in direct sunlight, and as cold as negative 180 degrees Celsius by night. Temperature varies this much due to the lack of atmosphere. Gases easily escape into space because the moon's gravity is so weak. The moon also has no liquid water. There may however be ice by the poles of the moon. This ice would be blocked from sunlight and be able to remain frozen.
#10 How did the moon form?
Scientists think that the moon may have formed by a planet-sized object colliding with the Earth. Material from the object and the Earth could have been ejected into orbit around the Earth. After that, gravity may have this material to form the moon.
This would have happened about 4.5 billion years ago when the Earth was very young. The solar system was full of rocky debris and some of this debris was the size of small planets.