A black hole is defined as a region of spacetime from which gravity prevents anything, including light, from escaping. The theory of general relativity predicts that a sufficiently compact mass will deform spacetime to form a black hole. Around a black hole, there is a mathematically defined surface called an event horizon that marks the point of no return. The hole is called "black" because it absorbs all the light that hits the horizon, reflecting nothing, just like a perfect black body in thermodynamics. Quantum field theory in curved spacetime predicts that event horizons emit radiation like a black body with a finite temperature. This temperature is inversely proportional to the mass of the black hole, making it difficult to observe this radiation for black holes of stellar mass or greater. Objects whose gravity fields are too strong for light to escape were first considered in the 18th century by John Michell and Pierre-Simon Laplace. History General relativity
Apollo 11Broadcast on live TV to a world-wide audience, Armstrong stepped onto the lunar surface and described the event as "one small step for [a] man, one giant leap for mankind." Apollo 11 effectively ended the Space Race and fulfilled a national goal proposed in 1961 by the late U.S. President John F. Framework Crew Each crewman of Apollo 11 had made a spaceflight before this mission, making it only the second all-veteran crew (the other being Apollo 10) in human spaceflight history. Collins was originally slated to be the Command Module Pilot (CMP) on Apollo 8 but was removed when he required surgery on his back and was replaced by Jim Lovell, his backup for that flight. Backup crew In early 1969, Anders accepted a job with the National Space Council effective August 1969 and announced that he would retire as an astronaut on that date. Support crew Duke, Lovell, and Haise at the Apollo 11 CAPCOM Flight directors Call signs Apollo 11 spacecraft. Insignia Mementos Mission highlights Lunar descent
Gravitational singularityA gravitational singularity or spacetime singularity is a location where the quantities that are used to measure the gravitational field become infinite in a way that does not depend on the coordinate system. These quantities are the scalar invariant curvatures of spacetime, which includes a measure of the density of matter. The two most important types of spacetime singularities are curvature singularities and conical singularities. Singularities can also be divided according to whether they are covered by an event horizon or not (naked singularities). According to general relativity, the initial state of the universe, at the beginning of the Big Bang, was a singularity. Interpretation Many theories in physics have mathematical singularities of one kind or another. Some theories, such as the theory of loop quantum gravity suggest that singularities may not exist. Types Curvature , which is diffeomorphism invariant, is infinite. Conical Naked Entropy
Moon landingClickable imagemap of the locations of all successful soft landings on the Moon to date. Dates are landing dates in UTC. Still frame from a video transmission, taken moments before Neil Armstrong became the first human to step onto the surface of the Moon, at 02:56 UTC on 21 July 1969. An estimated 500 million people worldwide watched this event, the largest television audience for a live broadcast at that time. Luna 2, the first object made on Earth to reach the surface of the Moon. A moon landing is the arrival of a spacecraft on the surface of the Moon. The United States' Apollo 11 was the first manned mission to land on the Moon, on 20 July 1969. There have been six manned U.S. landings (between 1969 and 1972) and numerous unmanned landings, with no soft landings happening from 1976 until 14 December 2013. Unmanned landings The Soviet Union achieved the first unmanned lunar soil sample return with the Luna 16 probe on 24 September 1970. Manned landings
Quasars: Definition & Facts About Brightest Objects in the UniverseShining so brightly that they eclipse the ancient galaxies that contain them, quasars are distant objects powered by black holes a billion times as massive as our sun. These powerful dynamos have fascinated astronomers since their discovery half a century ago. In the 1930s, Karl Jansky, a physicist with Bell Telephone Laboratories, discovered that the static interference on transatlantic phone lines was coming from the Milky Way. By the 1950s, astronomers were using radio telescopes to probe the heavens, and pairing their signals with visible examinations of the heavens. This artist's concept illustrates a quasar, or feeding black hole, similar to APM 08279+5255, where astronomers discovered huge amounts of water vapor. However, some of the smaller point-source objects didn't have a match. Light-speed jets Scientists now suspect that the tiny, point-like glimmers are actually signals from galactic nuclei outshining their host galaxies. Family tree — Nola Taylor Redd, SPACE.com Contributor
SputnikNASA Main Page Multimedia Interactive Feature on 50th Anniversary of the Space Age Sputnik and The Dawn of the Space Age History changed on October 4, 1957, when the Soviet Union successfully launched Sputnik I. The story begins in 1952, when the International Council of Scientific Unions decided to establish July 1, 1957, to December 31, 1958, as the International Geophysical Year (IGY) because the scientists knew that the cycles of solar activity would be at a high point then. In July 1955, the White House announced plans to launch an Earth-orbiting satellite for the IGY and solicited proposals from various Government research agencies to undertake development. The Sputnik launch changed everything. Immediately after the Sputnik I launch in October, the U.S. On January 31, 1958, the tide changed, when the United States successfully launched Explorer I. The Sputnik launch also led directly to the creation of National Aeronautics and Space Administration (NASA).
Miralda-EscudeJordi Miralda-Escudé Quasars are the most luminous objects known in our universe, and they are found in the centers of galaxies. Some quasars are as bright as 100 or 1000 times our galaxy the Milky Way, and this enormous amount of light is coming from a region so small that it appears point-like, in the center of the host galaxy, even with the most powerful telescopes we have. An example of what a distant quasar may look like when viewed with the Hubble Space Telescope and the Chandra X-ray Observatory is found in these images of PKS 1127-145 , one of these quasars that is so bright that you can't even see the galaxy around it because it is outshined by the light of the quasar. The first quasars were discovered in 1963, and shortly after their discovery astrophysicists theorized that they were perhaps being caused by very massive black holes. Here is a good website to learn the basics on Active Galaxies and Quasars . My recent publications related to this research J.
tumblr m6vzp8nKQk1rx06nvo1 r2 500Active Galaxies and Quasars - IntroductionActive galaxies are galaxies which have a small core of emission embedded in an otherwise typical galaxy. This core may be highly variable and very bright compared to the rest of the galaxy. Models of active galaxies concentrate on the possibility of a supermassive black hole which lies at the center of the galaxy. For "normal" galaxies, we can think of the total energy they emit as the sum of the emission from each of the stars found in the galaxy. There are several types of active galaxies: Seyferts, quasars, and blazars. Active galaxies are intensely studied at all wavelengths. A diagram of an active galaxy, showing the primary components. Seyfert Galaxies Of the two types of Active Galactic Nuclei (AGN) which emit gamma rays, Seyfert galaxies are the low-energy gamma-ray sources. Seyfert galaxies typically emit most of their gamma rays up to energies of about 100 keV and then fade as we observe them at higher energies. An artists concept of an active galactic nucleus Quasars Blazars