View Full Version : What keeps everything to be constant
maruseid
Nov 19, 2016, 03:30 PM
Since universe is expanding with an accelarated motion so what keep every revolving or rotating objects the same motion and distance?
Wondergirl
Nov 19, 2016, 03:41 PM
Gravity.
from http://earthsky.org/space/expanding-universe-earth-sun --
While astronomers do believe that the universe has been expanding since the Big Bang, this expansion works on the largest of scales, the scale of the galaxies. In other words, our solar system – our sun and its family of nine planets – is not expanding.
Earth is located 150 million kilometers – about 93 million miles – or 8 light-minutes from the sun. It’s thought to have been located at this distance from the sun since our solar system was born, some four-and-a-half billion years ago. So the sun isn’t getting farther from Earth. And, likewise, our sun isn’t getting farther from other stars in our own galaxy.
Why don’t the solar system and galaxy expand, while the universe as a whole does? The solar system and galaxy are held together gravitationally. Our Milky Way galaxy is a collection of hundreds of billions of stars. It’s thought to be one of billions of galaxies in the universe.
ma0641
Nov 20, 2016, 11:04 AM
Gravity plays the biggest part in keeping things in relative proportion. But you also need too realize that we can just barely see the end of our own solar system. A lot of the data is based on what Hubble can see in it's lens angle. When something is 100 million light years away, it will rotate but measuring expanding distance is near improbable. Except for possibly the nearest stars, thing look the same as they did to prehistoric man. Telescopes have been around for only about 400 years and it is said that the handle if the Big Dipper will look different in 50,000 years. Hmm, will man be around to record the change?