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Gravitational microlensing
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Diagram illustrating gravitational microlensing with three scenarios: a star's light passing by a lensing object, showing how the lens bends light toward Earth and creates a brighter or distorted view of the star as seen from Earth. The opening slide to the interactive. An illustration of a telescope under a starry sky.
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Nicolaus Copernicus. Nicolas Copernicus (1473-1543) Polish astronomer. In 1543 he published, forward proof of a Heliocentric (sun centered) universe. Coloured stipple engraving published London 1802. De revolutionibus orbium coelestium libri vi.
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Diagram illustrating gravitational microlensing with three scenarios: a star's light passing by a lensing object, showing how the lens bends light toward Earth and creates a brighter or distorted view of the star as seen from Earth.
Illustration of gravitational microlensing showing a lens moving between Earth and a distant star. When the lens (a massive object such as an extrasolar planet) is between Earth and the star, it increases the star's brightness.

Gravitational microlensing

astronomy
Written by
Kenneth Brecher
Professor of Astronomy and Physics; Director, Science and Mathematics Education Center, Boston University.
Kenneth Brecher
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Gravitational microlensing, brightening of a star by an object passing between the star and an observer. Since 2004 many extrasolar planets have been found through gravitational microlensing, including several so-called free-floating planets that do not orbit any star. This technique depends on an effect first discussed by physicist Albert Einstein. In his 1916 paper on general relativity, he showed how light that passed a massive object would be deflected by the object’s gravity. In this way, an extrasolar planet can act as a gravitational lens that would focus the light from a more distant star.

Kenneth Brecher