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.
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
As of 2014, there are 41 modern constellations, which are constellations added to the catalogue after 1600. Four of them, Carina, Puppis, Pyxis and Vela are derived from Argo, a constellation catalogued by Ptolemy.Full Answer >
Gravitational attraction is the force that draws two objects together. It is governed by the law of universal gravitation, which states that the force of attraction between two objects is related to the mass of the objects and inversely related to the distance between the two.Full Answer >
According to NASA, the temperature of a black hole with the mass of the sun is only one ten-millionth of a degree over absolute zero. Scientists determine this by measuring the temperature of the radiation that comes from a black hole.Full Answer >
Giant elliptical galaxies form early in the life of local galactic clusters as members of the group pass close by each other and begin to merge, according to John Dubinski for the Canadian Institute for Theoretical Astrophysics. In any sizable galactic cluster, some galaxies near the core of the group gravitationally interact with each other, exchange material and eventually fall together to form the core of the central elliptical giant.Full Answer >