How big is the universe?
The current, observable universe has been determined to have a width of 156 billion light years, with an error of less than 1%, by the latest deep-space telescope WMAP. At first, it might seem impossible that scientists are so sure of this astronomical measurement, but this figure has been narrowed by years of research and determined by several paths of inquiry. Also, the size of the universe is intimately dependent on its shape, age, acceleration, and total mass, so we are very confident in this figure. In 2003, the Wilkinson Microwave Anisotropy Probe sent back enough data for scientists to publish extremely dependable studies that established two previously unknown facts about the universe. They determined our universe is flat, which means standard Euclidean geometry is valid on the largest scale. This can be understood by saying a straight line more or less stays a straight line for as long as it extends. They also established that the universe is accelerating at an ever-increasing
On the plains of San Agustin, a vast new mexican valley filled with sagebrush and inhabited mostly by cattle, MIT radio astronomer Jacqueline Hewitt sits in the control room of the Very Large Array, a collection of 27 rail-mounted radio telescopes, each with a dish antenna more than 80 feet across. The antennas are positioned as far apart as possible, forming a Y with the control room at the center and the farthest telescope in each arm some 15 miles away. The dishes are all focused on a single point in the sky. Hewitt is tuning in on a quasar–a pointlike object billions of light-years away that radiates the energy of a million suns, mostly as radio waves. She is waiting for its signal to flicker. At the four-meter optical telescope atop Cerro Tololo, in the dry mountains of northern Chile, another MIT astronomer, John Tonry, is looking at galaxies, trying to measure the subtle differences in brightness across their surfaces. And at Cerro Tololo’s sister telescope, the four-meter on K
No one knows if the universe is infinitely large, or even if ours is the only universe that exists. And other parts of the universe, very far away, might be quite different from the universe closer to home. Future NASA missions will continue to search for clues to the ultimate size and scale of our cosmic home. Go on the full exploration of the size of our universe at: How big is our universe? Beautiful images and straight-forward methods and ideas take you from our solar system, into the realm of the stars, the galaxies and finally into the vast panorama of the observable universe. You can also download and print a pdf version of these explorations. + View site The Universe Forum talks more about size and distance in the universe. + View site Learn more about the recent transit of Venus. + View site Learn more about the WMAP satellite. + View site Learn more about WMAP education. + View site For kids 14 and up, check out investigations into the destiny of our universe. + View site NAS
by Brent Tully How big is the universe? Could it be infinitely large? If the universe has an edge, what is beyond the edge? And if the universe had a beginning, what was going on before that? Our experience of the everyday world does not prepare us to grasp the concept of an infinite universe. And yet, trying to imagine that the cosmos actually has a boundary does not make things any easier. There is an edge to what we are able to see and could ever possibly see in the universe. Light travels at 300,000 kilometers per second. That’s top speed in this universe—nothing can go faster—but it’s relatively slow compared to the distances to be traveled. The nearest big galaxy to our Milky Way, the Andromeda galaxy, is two million light-years away. The most distant galaxies we can now see are 10 or 12 billion light-years away. We could never see a galaxy that is farther away in light travel time than the universe is old—an estimated 14 billion or so years. Thus, we are surrounded by a “horizon
