At the equator, the Earth rotates at a speed of about 1, km per hour, but at the poles the movement speed is nearly nothing. For Earth to make one complete revolution around the Sun takes This amount of time is the definition of one year. The gravitational pull of the Sun keeps Earth and the other planets in orbit around the star.
The closest Earth gets to the Sun each year is at perihelion million km on about January 3rd and the furthest is at aphelion million km on July 4th. During one revolution around the Sun, Earth travels at an average distance of about million km. Earth revolves around the Sun at an average speed of about 27 km 17 mi per second, but the speed is not constant. We can calculate that with basic geometry. First, we have to figure out how far Earth travels.
Earth takes about days to orbit the sun. The orbit is an ellipse, but to make the math simpler, let's say it's a circle. So, Earth's orbit is the circumference of a circle. The distance from Earth to the sun — called an astronomical unit — is 92,, miles ,, kilometers , according to the International Astronomers Union. That is the radius r. So in one year, Earth travels about million miles million km. So, Earth travels about 1. Related: How Fast does Light Travel? The sun has an orbit of its own in the Milky Way.
The sun is about 25, light-years from the center of the galaxy, and the Milky Way is at least , light-years across. We are thought to be about halfway out from the center, according to Stanford University.
Even at this rapid speed, the solar system would take about million years to travel all the way around the Milky Way. The Milky Way, too, moves in space relative to other galaxies. In about 4 billion years, the Milky Way will collide with its nearest neighbor, the Andromeda Galaxy. The two are rushing toward each other at about 70 miles per second km per second. There is no chance that you'll be flung off to space right now, because the Earth's gravity is so strong compared to its spinning motion.
This latter motion is called centripetal acceleration. At its strongest point, which is at the equator, centripetal acceleration only counteracts Earth's gravity by about 0. In other words, you don't even notice it, although you will weigh slightly less at the equator than at the poles. NASA says the probability for Earth stopping its spin is " practically zero " for the next few billion years.
Theoretically, however, if the Earth did stop moving suddenly, there would be an awful effect. The atmosphere would still be moving at the original speed of the Earth's rotation. This means that everything would be swept off of land, including people, buildings and even trees, topsoil and rocks, NASA added.
What if the process was more gradual? This is the more likely scenario over billions of years, NASA said, because the sun and the moon are tugging on Earth's spin. That would give plenty of time for humans, animals and plants to get used to the change.
By the laws of physics, the slowest the Earth could slow its spin would be 1 rotation every days. As we consider increasingly large size scales, the speeds involved become absolutely huge!
The galaxies in our neighborhood are also rushing at a speed of nearly 1, kilometers per second towards a structure called the Great Attractor, a region of space roughly million light-years one light year is about six trillion miles away from us. This Great Attractor, having a mass quadrillion times greater than our sun and span of million light-years, is made of both the visible matter that we can see along with the so-called dark matter that we cannot see. Each of the motions described above were given relative to some structure.
Our motion about our sun was described relative to our sun, while the motion of our local group of galaxies was described as toward the Great Attractor. The question arises: Is there some universal frame of reference relative to which we can define the motions of all things? In , the COBE satellite was placed in orbit about the earth again, the earth is the frame of reference! This radiation, which remains from the immensely hot and dense primordial fireball that was our early universe, is known as the cosmic microwave background radiation CBR.
The CBR presently pervades all of space. It is the equivalent of the entire universe "glowing with heat. Because the CBR permeates all space, we can finally answer the original question fully, using the CBR as the frame of reference.
The earth is moving with respect to the CBR at a speed of kilometers per second.
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