As far as humans can tell, space is infinite; it has no end or borders. Scientists believe that space will always seem infinite to humans for two reasons. First, our investigation of space has never found an edge (or any indications of an edge). Second, measurements show that space is expanding faster and faster, which pushes the edges of the universe ? if there are any ? ever farther out.Know More
Space is continuing to expand (meaning that all the galaxies are speeding away from the center of the universe) because of the Big Bang's momentum and because of a substance called dark energy. Dark energy occupies the seemingly empty parts of the universe, but it has a strong negative pressure, pushing things away from each other even faster than they would move as a result of the Big Bang. This makes it difficult for humans to measure the farthest reaches of space.
In addition, anything traveling through space ? including humans' investigative tools, techniques and measurements ? is limited to the fastest possible speed: the speed of light. Because nothing can travel faster than light, there is a limit to how far scientists can explore or understand the universe. The size of the observable universe (the part astronomers could potentially study) is approximately 45.7 billion light-years across.Learn more in Universe
As of 2013, the National Aeronautics and Space Administration determined, with a margin of error of only 0.4 percent, that the universe is infinite in size. The observable universe extends 92 billion light years in diameter. The exact size of the universe, or if there are multiples, is unknown.Full Answer >
The no boundary theory of the universe likens the universe to the Earth, in that is impossible to find any boundaries traveling around the Earth or to fall off it. This is possible as a result of theorizing that prior to the Big Bang, the generally accepted laws of physics did not apply and that the concept of time as we know it did not exist.Full Answer >
About 1,700 extrasolar planets have been discovered so far, including 715 discoveries that were announced in February, 2014 by the National Aeronautical and Space Administration. The newest extrasolar planets were discovered when astronomers examined 305 stars with Kepler, NASA's first extrasolar planet mission. Extrasolar planets, also called exoplanets, are planets that exist outside of the solar system.Full Answer >
From Earth's surface, outer space begins at the somewhat-arbitrary Karman Line, or 100 km up, according to the Space website. From there, the observable universe stretches out without reaching any perceptible boundary.Full Answer >