Earth, Moon and Stars
By: Joshua Masters
Earth in Space
How Does Earth Move In Space?
Earth moves through space in two major ways: rotation and revolution.
Rotation is the spinning of Earth upon the imaginary line that is put through the Earth. The rotation causes the concepts that we call "day" and "night." Earth rotates eastward where Sun is perceived to move westward which in turn has the sun directed on certain hemispheres at separate times of the day.
Revolution is the movement of an object that moves around another. One completion of Earth's revolution around the Sun causes the "365 1/4 day year." The path that Earth follows in its revolution is called an orbit around the sun. This orbit is not completely circular, but an elongated circle, or ellipse.
What causes the cycle of seasons on Earth?
The Earth has seasons because the imaginary line that is its axis, is tilted as it revolves around the Sun.
If Earth's axis weren't tilted, but straight up and down with its orbit, temperatures would stay constant, and there would not be any seasons. The axis has a tilt of 23.5° from a vertical perspective which causes the Sun's light to direct upon certain hemispheres during the Earth's revolution.
Gravity and Motion
What determines the strength of the force of gravity between two objects?
Firstly gravity is the attractive force between objects; this is dependent upon the objects masses and the distance between them. Whereas gravity attracts all objects toward one another
The objects depend on the mass because if the mass were to increase the force of gravity would increase as well. The objects depend on distance because if distance increased, the force of gravity would decrease.
What two factors combine to keep the moon and Earth within their orbit?
The main factors that contribute to the orbits that the Earth and moon have kept are the force of gravity as well as inertia.
The force of gravity is what keeps the Earth and moon staying on their course because for instance, the Earth's gravity keeps pulling the moon toward it, keeping it from moving in a straight line but keeping orbit. Inertia is the tendency of an object to resist a change in motion, this force, if it weren't for Earth's gravity, inertia would cause the moon to move of its orbit, but if inertia weren't there, the moon would come to Earth and stay without revolving around on an orbit.
Phases, Eclipses, and Tides
What causes the phases of the moon?
A phase of the moon is dependent upon how much of the sunlit side of the moon faces Earth.
The phases of are the set of sides that you see each time the moon makes a full revolution around Earth. You can see the moon only because it reflects the light of the sun to Earth. Because the sun lights the moon, half of the moon is always lit by sunlight.
What are solar and lunar eclipses?
An eclipse is when the moon's shadow hits Earth or Earth's shadow hits the moon.
When and object comes in between the sun and a third object in space, it casts a shadow upon that object which is a eclipse. A solar eclipse occurs when the moon passes directly Earth and the sun by blocking sunlight from Earth. A lunar eclipse occurs when Earth blocks sunlight from reaching the moon.
What causes the tides?
Tides are caused by differences in how much the moon's gravity pulls on different parts of Earth.
There is a cycle of tides that form over time, they are made of two consecutive low and high tides called spring tides and neap tides. A spring tide is a tide with the greatest difference between consecutive low and high tides. A neap tide the tide with the least difference between consecutive low and high tides.
What features are found on the moon's surface?
The features of the moon's surface consist of maria, craters, and highlands.
Maria are dark, flat areas on the moon's surface formed from huge ancient lava flows that occurred 3-4 billion years before now.
Craters are large, round pits that are caused by the impact of a meteoroid.
Highlands are some of the light-colored features that Galileo saw on the moon's surface.
What are some of the characteristics of the moon?
The largest and most visible differences in comparison to Earth is that the moon is dry and airless, it is much smaller and has a variation on its surface temperature.
The moon's size and density are also important characteristics consist of 3,476 km is diameter; about ≈ 1/4 of the Earth's diameter. The mass of the moon is ≈ 1/80 of Earth's mass.
The moon's temperature ranges from about 130°C (266°F) in direct sunlight, to a frigid -180°C (-292°F); the temperatures vary so much because there is no atmosphere.
The moon as well in comparison to Earth has no liquid water and all, however there is evidence that there may be large patches or sections of ice near the cooler ends of the moon.
How did the moon form?
The most popular theory of how the moon formed is that a planet-sized object collided with Earth to break of a section to form the moon.
There is much evidence to contribute to this theory, for example, that when Earth was a younger planet about 4.5 billion years ago, the Milky Way was full of rocky debris that were sizes similar to small planets.