Earth, Moon, and Sun
By: Elly Alarie
Section 1 Earth in Space
#1 How Does Earth Move in Space?
The study of the moon, stars, and other objects in space is called astronomy. Earth rotates around the Sun. Although it may seem that the Sun goes around Earth, it just appears that way because earth is tilted on its axis. The imaginary line that passes through Earth's center and the North and South poles is Earth's axis.
Day and night is caused by Earth's rotation. The spinning of Earth on its axis is called rotation. As Earth rotates, it's facing away from the sun, so it gets darker and colder outside. Then, as the Earth completes its rotation, it gets lighter and warmer causing day.
Calendars are based off of the moon and stars. A calendar is a system of organizing time that defines the beginning, length, and divisions of a year. Ancient Egyptians made their calendar based off of how long the star Sirius takes to reappear in the sky. They found that it takes 365 days. People divided mouths base on the moon cycle. The moon cycle is 29.5 day but when added up in twelve months, it only equals 354 days. Their calendar had twelve months of thirty days and five added days onto the end. However, today's calendar is different. We found that the earth's year is 365.25 days. The amount of days we have in a year is 365 days so, every four years, there is something called a "leap" year in which we add an extra day to the end of February.
#2 What Causes the Cycle of Seasons on Earth?
Outside the tropic and polar regions, there are season. There are spring, winter, summer, and autumn. However temperature varies depending on where you are. The equator gets the most direct sunlight because its in the middle of the Earth so, when the earth revolves around the sun, the equator neither leans closer or farther away from the sun. This causes the temperature to be greater than the rest of the world. However, the poles receive sunlight at a steep angle so its colder there. Without Earth's axis, we would have around the same temperatures all the time because the amount of direct sunlight would never change. That also means there would be no seasons because the varying temperatures is what make the season.
In June, the northern hemisphere is tilted toward sun. Even though it may seem that since the sun is farther away that it would be colder, the sun actually is out for longer and creates a longer day. In June, the northern hemisphere is in summer and the southern hemisphere is in winter.
In December, it is summer in the southern hemisphere and winter in the northern hemisphere. The southern half of the Earth is facing towards the sun, and is getting more hours of daylight making it summer there. Its the opposite up north. There are shorter days and less direct sunlight so it is winter.
There are two days a year when earth is farthest away from the sun. These days are known as the solstice. Halfway between the solstice is called the equinox.This occurs when the noon sun is directly overhead at the equator.
Section 2 Gravity and Motion
#3 What determines the strength of the force of gravity between two objects?
A force keeps Earth and the Moon in orbit. A force is a push or pull. Isaac Newton discovered this. He also discovered that there is a force called gravity that attracts all objects toward each other. He created a law called the law of universal gravitation. It states that every object in the universe attracts each other. The strength of gravity depends on the masses of the objects and the distance between them. Mass is the amount of matter in an object.
Weight can change depending on its location and how strong the gravity is. Weight is the force of gravity on an object.
#4 What two factors combine to keep the moon and Earth in orbit?
Inertia keeps the moon from crashing in to Earth and keeps Earth from crashing into the sun. Inertia is the tendency of an object to resist a change in motion. The more the mass an object has, the greater the inertia. Isaac Newton created a law called Newton's first law of motion. It states that an object at rest will stay at rest and an object in motion will stay in motion with a constant speed and direction unless acted on by a force.
Newton said that the two factors that keep the Earth in orbit with the sun and the moon in orbit with Earth are inertia and gravity.The Earth pulls the moon toward it but because of it inertia, it keeps moving ahead. The same thing happens with the Earth and sun.
Section 3Phases,Eclispses, and Tides
#5 What causes the phases of the moon?
The same side of the moon always faces the Earth. Its called the "near side" and the side of the moon facing away from us is called the "far side". The moon, Earth, and sun changing positions causes eclipses, tides, and the phases of the moon.
The moon doesn't actually produce light. It reflects the sun's light. The moon goes through phases that we see as it revolves around the earth. The different shapes of the moon you see from earth are called phases. Depending on the angle the sunlight is coming in from the sun effects the shape we see from earth of the moon.
#6 What are solar and lunar eclipses?
If an object in space becomes in between the sun and another object, it casts a shadow, creating an eclipse. Two types of eclipses are solar and lunar. Solar is Latin for "sun" and lunar is Latin for "moon". A solar eclipse is caused when the moon passes directly between the sun and Earth. That casts a shadow on earth from the moon. From any place in the moon's umbra, sunlight is completely blocked. The umbra is the very darkest part of the moon's shadow. In the penumbra, the sun can be partly seen from Earth. The penumbra is part of the moon's shadow but isn't as dark at the umbra. A lunar eclipse happens when the moon goes into the earth's shadow. That means that you cant see the moon at all be because Earth is blocking the sunlight. Lunar eclipses are more likely to see than solar eclipses.
#7 What causes the tides?
The moon's gravity on earth creates tides. Tides are the rise and fall of ocean water that occurs every 12.5 hours or so. The water rises in a period of six hours, then falls for about six hours. During a high tide, they moons gravity is greater and during a low tide, the gravity is lower. At any given time, there will always be two low tides and two high tides on Earth. A spring tide is combined forces of gravity from the sun and moon producing a tide with the greatest difference between consecutive low and high tides. A neap tide is created when the line between Earth and the sun is at a right angle to the line between the Earth and the moon. A neap tide is a tide with the least difference between consecutive low and consecutive high tides. They occur twice a month.
Section 4 Earth's Moon
#8 What features are found on the moon's surface?
Telescopes help find out more about the moon. A telescope is a device built to observe distant objects by making them appear closer. Galileo discovered that the moon had many different features on it rather than a smooth surface. There are specific names for the features in the moon. Some are maria, craters, and highlands. The dark, flat areas on moon's surface is maria. Craters are large round pits on the surface of the moon. They are created by meteoroids. Meteoroids are chunks of rocks or dust from space. Highlands are mountains on the moon. They create large shadows and cover most of the moon.
#9 What are some characteristics of the moon?
The moon's origin is based off a theory called the "collision-ring theory". At about 4.5 billion years ago, scientists believe that a planet-sized object collided with the Earth to create the moon. Material from the object in Earth went into a ring in orbit around the Earth and gravity caused the material to form into the moon.
#10 How did the moon form?
The moon is the closest planet to Earth in space. The moon is very different, however. Instead of the moisture filled air on Earth, the moon is very dry and airless. The moon is small compared to Earth, and the has large variations of temperature. The moon is 3,476 kilometers in diameter. That is a little smaller than the United States. A similarity between Earth and the moon is its structure of density. It is harder in the core and gets less dense as you move farther away. There is no atmosphere on the moon. That means the temperatures vary a lot. It can range anywhere from 130 to -180 degrees Celsius. The moon has no water but there has been evidence that there may be ice patches near the poles.
Happy Birthday, Moon!
Celebrate the anniversary of the first steps on the moon! (Space suits not included)
Watch this video to get informed about the seasons, moon phases, and tides. We encourage you to take the time of watching it so we can insure that you know about the moon for the moon celebration.