Earth, Moon(s) and Sun
In this Chapter, we are learning about the Earth, Earth's main moon and the Sun. I have added an extra part to this presentation about our second moon, Cruithne.
By Cassandra Berlin
Earth in Space
What causes the cycle of seasons on Earth?
The Earth is tilted on its axis. When sunlight hits the surface directly, it is warmer than if the sunlight hits the earth less directly. The reason that the equator is warm is because the sun hits there the most directly all year around. At the poles, the sun hits earth at an angle. It is the same amount of energy spread out over a larger distance, therefor making it colder. On the summer solstice, the northern hemisphere is tilted towards the sun, making it warm in the northern hemisphere. It is the exact opposite with the winter solstice. Earth's Southern hemisphere is tilted toward the sun, making the rays indirect in the northern hemisphere, therefor cold up north and warmer down south.
How does Earth Move in Space?
Earth moves in space in two ways, revolution and rotation. Earth Revolves, or moves around the Sun. It also rotates, or spins on its axis. It takes earth one year or 365.242 days to make one revolution around the sun. It takes Earth only 1 day or 23 Hours, 56 minutes and 4.1 seconds. However, a phenomenon due to tides raised by the Moon slow Earth's rotation. Because of the way the second is defined, the mean length of a day is now about 86,400.002 seconds, and is increasing by about 1.7 milliseconds per century (an average over the last 2,700 years.
Gravity and Motion
What determines the strength of the force of gravity between two objects?
Mass and distance both effect the strength of the force of gravity. If the mass of an object increases, force of gravity also increases. If the mass of an object decreases, the force of gravity does too. If the distance between two objects increases, the force decreases. If the distance between the two objects decreases, the force increases.
What two factors combine to keep the moon and Earth in orbit?
Inertia and gravity keep both the Earth and the moon in orbit. Earth's gravity is constantly pulling the moon toward it. This prevents the moon from moving in a straight line. Though being pulled, inertia makes it so the moon is being pulled forward at the same time. The Earth and sun have the same relationship. The sun's gravity pulls Earth toward it, but Earth's inertia moves it forward.
Phases, Eclipses and Tides
What causes the phases of the moon?
The phases of the moon depend on how much of the sunlit side of the moon faces Earth. The phases are causes by changes in position of the sun, Earth, and moon. The sun lights up the moon, so half of the moon is in direct sunlight. The moon is seen from different angles, so the half of the moon that the sun lights up isn't always facing Earth, therefor isn't visible.
What are solar and lunar eclipses?
A solar eclipse is when the moon's shadow hits earth, and it comes in between the sun and earth. The result is a black, dark moon and a fiery, white outline. A lunar eclipse is when earth blocks sunlight from hitting the moon. The moon can become red from Earth's atmosphere reflecting some sunlight on the moon.
What causes the tides?
The moon causes the tides. They are caused by the differences in how much the moons gravity pulls of different parts of the Earth. The force of gravity pulls the moon and Earth (with everything on it including water) toward each other. A spring tide is when there is the largest difference between high and low tides. A neap tide is the smallest difference between high and low tides.
What are some features found on the
1. Maria- The moon contains dark, flat areas that were thought to be lakes. Actually, the moon has no water.The Maria actually is hardened rock formed from lava flows that occurred 3-4 billion years ago.
2. Craters- Large round pits, negative space. Many scientist thought that the craters were made by volcanoes, when actually they were made by the impact of meteoroids, or chunks of rocks and or dust hitting the moon's surface.
3. Highlands- Mountains. These are the lighter colored areas of the moon. This takes up a large portion of the moon's surface.
What are some characteristics of the moon?
Size- The moon's diameter is just under the distance across the contiguous United States. It measures exactly 3,476 kilometers across. It has only 1/80 as much mass as Earth does.
Density- The average density of the moon is very similar to Earth's density on the outer layers. The inner layers of Earth are much more dense than the moon and Earth's outer layers. This is why the moon has only 1/80 of the mass of earth though it isn't 1/80 of the size.
Temperature- The moon has no atmosphere, so temperature varies a lot. The temperature can range from 130 degrees Celsius to -180 degrees Celsius.
Atmosphere- The moon has no atmosphere. All of the gasses on the moon escaped. There is no way to keep all of the gasses or heat on the moon, so the temperature ranges.
Water- The moon has no water in the form of a liquid. There is evidence of ice at the moon's poles, where some areas are shades from sunlight. If humans were to colonize the moon, then the ice would be valuable.
How did the moon form?
There are many theories about how the moon was formed. The most widely accepted and most realistic theory based on the evidence collected is the collision-ring theory. The scientists theorize that a planet sized object collided with Earth to form the moon. Material from the object collected into the moon and orbited Earth because of gravity.
Our Moon Phase Project
What part of the Earth did I look at the moon from?
Please RSVP to the Eclipse Party. It is on September 25, 2015. The party starts at 6:00 and ends when the eclipse does.
Blue Moon Watch July 31, 2015, the second full moon of the month.
3753 Cruithne: Our Second Moon
3753 Cruithne is Earth's unknown second moon.
Is it really a moon?
The dictionary defines moon as a natural satellite that orbits a planet. 3753 Cruithne is an asteroid that is orbiting Earth. It is naturally formed, most likely the same way our known moon was formed. So, yes 3753 Cruithne would be considered our moon.
Why haven't we learned about this?
Scientists debate over if 3753 Cruithne should be considered a planet or not. 3753 Cruithne is a co-orbital object. It orbits the Earth at times, but its main orbit is the sun. 3753 Cruithne takes approximately 1 year to orbit the sun, but takes about 770 years to fully complete its horseshoe orbit around Earth. Also, this moon wasn't discovered until 1986, but all of our ancestors worshiped our main moon.
Fun Facts about 3753 Cruithne
1. 5 kilometers across.
2. Discovered on October 10, 1986, by Duncan Waldron.
3. The closest it comes to Earth is 12 million kilometers away, which is 30 times the separation of our main moon. This happens every November.
4. No danger of collision of Earth for millions of years, but most likely not ever.
5. Has a horseshoe orbit, is a type of co-orbital motion of a small orbiting body relative to a larger orbiting body.
6. Takes 770 years to orbit Earth while orbiting the sun.