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Consequently, a gravitational lens has no single focal point, but a focal line. The term "lens" in the context of gravitational light deflection was first used by O. J. Lodge, who remarked that it is "not permissible to say that the solar gravitational field acts like a lens, for it has no focal length". [11]
The first term is the straight path travel time, the second term is the extra geometric path, and the third is the gravitational delay. Make the triangle approximation that α ( z ) = θ − β {\displaystyle \alpha (z)=\theta -\beta } for the path between the observer and the lens, and α ( z ) ≈ ( θ − β ) D d D d s {\displaystyle \alpha ...
One of the consequences of general relativity is the gravitational lens. Gravitational lensing occurs when massive objects between a source of light and the observer act as a lens to bend light from this source. Lensing does not depend on the properties of the mass; it only requires there to be a mass.
For a source right behind the lens, θ S = 0, the lens equation for a point mass gives a characteristic value for θ 1 that is called the Einstein angle, denoted θ E. When θ E is expressed in radians, and the lensing source is sufficiently far away, the Einstein Radius, denoted R E, is given by =. [2]
An event called gravitational lensing allowed astronomers to discern a star 9 billion light-years away.
An Einstein Ring is a special case of gravitational lensing, caused by the exact alignment of the source, lens, and observer. This results in symmetry around the lens, causing a ring-like structure. [2] The geometry of a complete Einstein ring, as caused by a gravitational lens. The size of an Einstein ring is given by the Einstein radius.
Gravitational microlensing is an astronomical phenomenon caused by the gravitational lens effect. It can be used to detect objects that range from the mass of a planet to the mass of a star, regardless of the light they emit.
If they're able to use the sun as a giant gravity lens, NASA could see features the size of Central Park on distant planets.