The Moon does orbit the Earth
The Moon and the Earth have been connected in their orbits around the sun for over four billion years. The gravity and orbit of each celestial object affects the other. The Earth is only about thirty million years older than the Moon, and when the Moon first formed, it was ten to twenty times closer to Earth than it is now. This closeness of the Moon and Earth in the early evolution of our planet is likely the cause of the development of plate tectonics in the Earth’s crust, forming the continents and land masses of the Earth. The Moon’s gravity and orbit continue to affect life on Earth through total eclipses, ocean and river tides, and phases of the Moon.
One Face of the Moon
The Earth’s moon is large as planetary satellites go. Its size and distance from Earth have several effects. One is that the Moon and Earth have traded energy over millions of years as they orbit together. The Moon’s gravity has slowed the speed of the Earth’s rotation, and the Earth’s gravity has increased the speed of the Moon’s rotation. Over millions of years, the two bodies have become synchronous in their orbits, with the Moon always showing only one side toward the Earth.
The size of the Moon and its distance from Earth also result in the Moon and Sun appearing to be about the same size in the sky, although the Moon is actually millions of times smaller than the Sun. Because the Sun and Moon appear to be the same size, when the Moon moves between the Earth and the Sun, the result is a total lunar eclipse. The existence of lunar eclipses has had a profound effect on the development of many myths and religions of the world.
Ocean Tides and Moon Phases
The force of gravity becomes weaker as distance increases. The Moon’s gravity has a stronger effect on the side of the Earth, which is closer to the Moon. Because the Moon orbits around the Earth slightly faster than the Earth orbits on its own axis, the Moon pulls a bulge of water in the ocean around with it.
This bulge of ocean water creates ocean and river tides. With the tides, the level of the water rises and falls between one and ten meters several times a day along coastlines and in river estuaries. This creates environmental and ecological conditions important to many forms of oceanic and terrestrial life.
Also, because the Moon orbits the Earth slightly faster than the Earth rotates on its own axis, the Moon goes through phases from full moon to crescent moon to new moon during the course of a month. The speed of the Moon’s orbit relative to Earth’s orbit causes the Moon to advance in the sky hour by hour and day by day relative to the fixed stars in the background.
As this progression moves along, the percentage of the Moon which is illuminated by the sun changes, creating the phases of the Moon. The existence of lunar phases gave humanity an important way of tracking time and leading to crucial advances in the history and development of agriculture and civilization.
“If We Had No Moon – Astrobiology Magazine.” Astrobiology Magazine. N.p., 2007. Web. 15 June 2016.
“Lunar Phase Simulator – Lunar Phases – NAAP.” Lunar Phase Simulator – Lunar Phases – NAAP. N.p., n.d. Web. 15 June 2016.
“About the Moon.” Solar System Exploration. N.p., n.d. Web. 15 June 2016.