Note the gravitational lens ing effect, which produces two enlarged but highly distorted views of the Cloud.

Simulation of gravitational lens ing by a black hole, which distorts the image of a galaxy in the background (: File: BlackHole Lensing. gif | larger animation )

: Microlensing occurs when the gravitational field of a star acts like a lens, magnifying the light of a distant background star.

Such a strong gravitational field acts as a gravitational lens and bends the radiation emitted by the star such that parts of the normally invisible rear surface become visible.

In 1979 the gravitational lens effect predicted by Einstein's General Theory of Relativity was confirmed observationally for the first time with images of the double quasar 0957 + 561.

The first such gravitational lens to be discovered was the double-imaged quasar Q0957 + 561 ( or Twin Quasar ) in 1979 A grouping of two or more quasars can result from a chance alignment, physical proximity, actual close physical interaction, or effects of gravity bending the light of a single quasar into two or more images.

See also gravitational lens.

A gravitational lens refers to a distribution of matter ( such as a cluster of galaxies ) between a distant source ( a background galaxy ) and an observer, that is capable of bending ( lensing ) the light from the source, as it travels towards the observer.

Unlike an optical lens, maximum ' bending ' occurs closest to, and minimum ' bending ' furthest from, the center of a gravitational lens.

Consequently, a gravitational lens has no single focal point, but a focal line instead.

The observer may then see multiple distorted images of the same source ; the number and shape of these depending upon the relative positions of the source, lens, and observer, and the shape of the gravitational well of the lensing object.

Einstein realized that it was also possible for astronomical objects to bend light, and that under the correct conditions, one would observe multiple images of a single source, called a gravitational lens or sometimes a gravitational mirage.

It was not until 1979 that the first gravitational lens would be discovered.

* Cosmic shear, an effect of distortion of image of distant galaxies due to deflection of light by matter, as predicted by general relativity ( see also gravitational lens )

The gravitational lens effect of this intermediate galaxy bends the quasar's light so that it follows two paths of different lengths to Earth.

* astro-ph / 0302547 CSL-1: a chance projection effect or serendipitous discovery of a gravitational lens induced by a cosmic string?

Abell 2218 was used as a gravitational lens to discover the most distant known object in the universe as of 2004.

An Einstein Ring is a special case of gravitational lensing, caused by the exact alignment of the source, lens and observer.

The geometry of a gravitational lens

( 1998 ) via optical follow-up with the Hubble Space Telescope of a gravitational lens imaged with MERLIN.

* 1919 – Arthur Eddington: Our sun as gravitational lens, a proof of the Theory of relativity

With the definitions used before 2012, the astronomical unit was dependent on the heliocentric gravitational constant, that is the product of the gravitational constant G and the solar mass M < sub >☉</ sub >.

Dark matter's existence is inferred from gravitational effects on visible matter and gravitational lensing of background radiation, and was originally hypothesized to account for discrepancies between calculations of the mass of galaxies, clusters of galaxies and the entire universe made through dynamical and general relativistic means, and calculations based on the mass of the visible " luminous " matter these objects contain: stars and the gas and dust of the interstellar and intergalactic medium.

In 1921, his third year at the university, he published his first scientific works in the Italian journal Nuovo Cimento: the first was titled: On the dynamics of a rigid system of electrical charges in translational motion ; the second: On the electrostatics of a uniform gravitational field of electromagnetic charges and on the weight of electromagnetic charges.

The gravitational weakening of light from high-gravity stars was predicted by John Michell in 1783 and Pierre-Simon Laplace in 1796, using Isaac Newton's concept of light corpuscles ( see: emission theory ) and who predicted that some stars would have a gravity so strong that light would not be able to escape.

Using the principle of equivalence, Einstein concluded that the same thing holds in any gravitational field, that the rate of clocks R at different heights was altered according to the gravitational field g. When g is slowly varying, it gives the fractional rate of change of the ticking rate.

The changing rates of clocks allowed Einstein to conclude that light waves change frequency as they move, and the frequency / energy relationship for photons allowed him to see that this was best interpreted as the effect of the gravitational field on the mass – energy of the photon.

It was shown that the relativistic gravitational interaction arises as the small-amplitude collective excitation mode whereas relativistic elementary particles can be described by the particle-like modes in the limit of low momenta.

For him, the fact that his theory gave a straightforward explanation of the anomalous perihelion shift of the planet Mercury, discovered earlier by Urbain Le Verrier in 1859, was important evidence that he had at last identified the correct form of the gravitational field equations.

The mission was re-profiled to use several gravitational slingshots, referred to as the " VEEGA " or Venus Earth Earth Gravity Assist maneuvers, to provide the additional velocity required to reach its destination.

This was first shown by Newton, whose shell theorem mathematically predicts a gravitational force ( from the shell ) of zero everywhere inside a spherically symmetric hollow shell of matter, regardless of the shell's thickness.

rightThe Mariner 10 spacecraft launched on November 3, 1973 and was the first to use a gravity assist trajectory, accelerating as it entered the gravitational influence of Venus, then being flung by the planet's gravity onto a slightly different course to reach Mercury.

Astronomers believe that the matter composing the Oort cloud formed closer to the Sun and was scattered far out into space by the gravitational effects of the giant planets early in the Solar System's evolution.

" In 1931, Ernest W. Brown asserted, using a mathematical formula, that the observed irregularities in the orbit of Uranus could not be due to the gravitational effect of a more distant planet, and thus that Lowell's supposed prediction was " purely accidental.

It was suggested, for example, that the redshift of quasars was not due to the expansion of space but rather to light escaping a deep gravitational well.

As was emphasized above, quantum gravitational effects are extremely weak and therefore difficult to test.

However, ROTT's engine was still the first to pioneer myriad features which would be found in many later games, such as panoramic skies, simulated dynamic lighting, fog, bullet holes, breakable glass walls, level-over-level environments ( made possible by " gravitational anomaly disks "; suspended objects that collectively form stairs, floors, etc.

During the 1970s it was realized that gravitational time dilation caused the second produced by each atomic clock to differ depending on its altitude.

Also general relativity was confirmed many times, the classic experiments being the perihelion precession of Mercury's orbit, the deflection of light by the Sun, and the gravitational redshift of light.

Severed from vital interplanetary trade routes ( Tékumel is a world very poor in heavy metals ) and in the midst of a massive gravitic upheaval due to the lines of gravitational force between the stars being suddenly cut, civilization was thrown into chaos.

Since gravitational effects are all around us, it is impossible to pin down the exact date when humans first discovered gravitational mass.

When astronomers discovered the third member, they confirmed that the sources were separate and not the result of gravitational lensing.

Gary Flandro, an aerospace engineer at the Jet Propulsion Laboratory on the study team, discovered that the alignment of the outer planets would make it possible to use gravitational assists from Jupiter to go to Saturn, and thence and on to Uranus and Neptune.

Most of the gravitational lenses in the past have been discovered accidentally.

Einstein discovered that there were two operational definitions of " mass " being used by scientists: inertial, defined by applying a force and observing the acceleration, from Newton's Second Law of Motion ; and gravitational, defined by putting the object on a scale or balance.

It is named for Isaac Newton, who first discovered it and proved that it was a harmonic function in the special case of three variables, where it served as the fundamental gravitational potential in Newton's law of universal gravitation.

These planets were discovered by precise measurements of the radial velocity of the star, with the planets revealing their presence by their gravitational displacement of the star during each orbit.

discovered that galaxy G1 is part of a galaxy cluster which increases the gravitational deflection and can explain the observed distance between the images.

baryon acoustic oscillation feature, discovered in 2005 in the predicted location ; the polarisation of the CMB ; and the statistics of weak gravitational lensing.

With Dieter Brill in 1964, he discovered the Brill – Hartle geon, an approximate solution realizing Wheeler's suggestion of a hypothetical phenomenon in which a gravitational wave packet is confined to a compact region of spacetime by the gravitational attraction of its own field energy.

The orbit has decayed since the binary system was initially discovered, in precise agreement with the loss of energy due to gravitational waves predicted by Einstein's general theory of relativity.

In 1960, Trautman and Ivor Robinson discovered an important family of exact solutions of the Einstein field equation, the Robinson-Trautman gravitational waves.

In particular, they discovered an exact solution which models two gravitational plane waves which collide, interact nonlinearly, and create in the interaction zone a curved region of spacetime which is locally isometric to the Kerr vacuum.