Earth, Moon, and Sun
Earth in Space
Earth moves through space in a rotation and revolution. Rotation is the spinning of Earth on its axis. Revolution is the movement of one object around another. Earth rotates eastward on its axis.
The cycle of seasons on Earth is caused by the tilt of Earth's axis as it revolves around the sun. The seasons change based on the hemisphere that is pointed towards the sun and the amount of sunlight that area gets.
Gravity and Motion
The strength of the force of gravity between two objects is determined by distance. An increase of distance cause a rapid decrease of gravity force and if distance decreases, force increases.
Inertia and Gravity are combined to keep the moon and Earth in orbit. Inertia allows the moon and Earth to resist collision. Gravity is the reason why Earth doesn't fall into the sun or why the moon doesn't crash into Earth.
Phases, Eclipses, and Tides
The phases of the moon are caused by how much of the sunlit side of the moon faces Earth. Phases are the different shapes of the moon you see from Earth. During every complete revolution around Earth, the moon goes through a whole set of phases.
A solar eclipse occurs when a new moon blocks your view of the sun. A lunar eclipse occurs at a full moon when Earth is directly between the Earth and the sun.
Tides are caused by mainly by differences in how much the moon's gravity pulls on different parts of the Earth. Spring tides and neap tides are both caused by gravity.
The moon has features on its surface such as maria, craters, and highlands. Maria is what Galileo called dark, flat areas. Craters are large round pits that mark the moon's surface. Craters were created by the impact of meteoroids against the moon. Highlands are the light-colored features (like mountains) that Galileo saw on the moon's surface.
Some characteristics of the moon is dry, airless, small compared to Earth, and has large variations on its surface temperatures. The only form of water found on the moon is ice patches. The moon's temperature ranges from 130 degrees Celsius to -180 degrees Celsius. The moon is about one-fourth of Earth's diameter. The moon is 3,476 kilometers in diameter.
The moon was formed by a planet-sized object that collided with Earth. Material from the object and Earth's outer layers was put into orbit around Earth, where a ring was formed. Due to gravity, this material later combined to form the moon.
Want to walk on the moon?
Remember to bring your space suit and moon boots.