Why moon stays in orbit

However in winter the Northern Hemisphere is tilted away from the Sun giving us shorter days and cooler weather. If this were to change, and the Earth became unstable, then parts of the world could experience much greater temperature swings than we are used to through any given year, with freezing Arctic temperatures in winter followed by blazing hot temperatures in summer.

As humans we have the ability to adapt to our local surroundings to meet our needs. If humans are still around when and if it happens it is quite likely we would survive these massive changes with air conditioning in the summer and a lot of heating in winter. Unfortunately most animals are not so adaptable and if these changes happened rapidly due to an unstable planetary wobble, then most animals would not be able to evolve quickly enough to hibernate or migrate out of harm's way.

The human race has little to fear at present. By the time any change occurred, humans might even have generated technology that could speed up the Earth's rotation or transport us to other liveable planets within our galaxy. Do we really need the Moon? Update 19 July This story has been amended to clarify that previous references to the Moon "speeding up" actually refer to it moving into a higher orbit.

Moon's mighty ridge stirs debate. Moon's water is 'useful resource'. What keeps the moon in orbit around the earth? Feb 19, The earth 's gravity. Explanation: Like any object in orbit, an orbit is maintained, as according to Newton's first law of motion, by a combination of speed and gravity.

Related questions At what time of the day is the moon closest to earth? Why do the centripetal and centrifugal forces exactly balance each other? Because otherwise the Moon would come crashing into Earth. But why does the Moon not come crashing into Earth?

Because the centrifugal force exactly balances the centripetal force. The reasoning here is circular: the simple explanation above provides a way of understanding how the Moon stays in orbit around the Earth, but not exactly why. The why was only supplied by Einstein in the early s. A more thorough answer to "Why does the Moon stay suspended in the air?

We think that Einstein's Theory of General Relativity explains the properties of space and time in the Universe. Within that theory, objects with mass curve spacetime in their vicinity, and this curvature influences the motions of other objects. The greater the mass and density of the object, the larger the curvature of spacetime that results. So, the Moon orbits the Earth because the Earth curves spacetime in the vicinity of the Moon.

Though the Moon itself curves space as well since it has mass , the curvature in the vicinity of the Moon is dominated by the Earth, which "tells" the Moon to orbit the Earth, given the Moon's current position and motion in the sky. It is this interplay between mass and curvature that causes the gravitational and the centripetal forces in the first place, and thus why the simple explanation holds.

First case: - Why does the Moon orbit the Earth? It just does. And you can understand how it does by analyzing the forces on the Moon caused by its orbit and finding the forces pushing in and out are equal. Second case: - Why does the Moon orbit the Earth? Because the Earth distorts spacetime in the vicinity of the Moon, and causes it to orbit the Earth the way it does and the balance of forces to come out the way it does.

Kristine studies the dynamics of galaxies and what they can teach us about dark matter in the universe. She got her Ph. Kristine's email:. How does the Moon stay "suspended" in the air? Sometimes the far side is called the dark side of the moon, but this is inaccurate. When the moon is between the Earth and the sun, during one of the moon phases called the new moon, the back side of the moon is bathed in daylight.

The orbit and the rotation aren't perfectly matched, however. The moon travels around the Earth in an elliptical orbit , a slightly stretched-out circle. When the moon is closest to Earth, its rotation is slower than its journey through space, allowing observers to see an additional 8 degrees on the eastern side. When the moon is farthest, the rotation is faster, so an additional 8 degrees are visible on the western side.

Related: The moon: 10 surprising lunar facts. If you could journey around to the far side of the moon as the Apollo 8 astronauts once did, you would see a very different surface from the one you are accustomed to viewing. While the near side of the moon is smoothed by maria — large dark plains created by solidified lava flows — and light lunar highlands, the far side is heavily cratered.

Although you can't see the back side of the moon from Earth, NASA and other space agencies have glimpsed it with satellites. The rotational period of the moon wasn't always equal to its orbit around the planet. Just like the gravity of the moon affects ocean tides on the Earth, gravity from Earth affects the moon.