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A Terrestrial Atmospheric Lens (TAL) is a theoretical method of using the Earth as a large lens with a physical effect called
A Terrestrial Atmospheric Lens (TAL) is a theoretical method of using the Earth as a large lens with a physical effect called atmospheric refraction
Atmospheric refraction is the deviation of light or other electromagnetic wave from a straight line as it passes through the atmosphere due to the variation in air density as a function of height. This refraction is due to the velocity of ligh ...
.
The sun's image appears about a half degree above its real position during sunset due to Earth's atmospheric refraction.
In 1998, NASA astrophysicist Yu Wang from the Jet Propulsion Laboratory
The Jet Propulsion Laboratory (JPL) is a federally funded research and development center and NASA field center in the City of La Cañada Flintridge, California, United States.
Founded in the 1930s by Caltech researchers, JPL is owned by NASA an ...
for the first time proposed to use the Earth as an atmospheric lens.
Wang suggests in his paper that:''If built, the terrestrial atmospheric lens would become the largest telescope ever built. Its high resolution would allow to directly image nearby Earth-like planets with a level of detail never seen before. As of September 2020, the main observation targets are''If we could build a space telescope using the Earth's atmosphere as an objective lens the aperture of such space telescope would be the diameter of the earth. Telescope resolution could be enhanced by up to seven orders of magnitude and would enable detailed images of planets in far away stellar systems.'' ''
Proxima b
Proxima Centauri b (or Proxima b), sometimes referred to as Alpha Centauri Cb, is an exoplanet orbiting in the habitable zone of the red dwarf star Proxima Centauri, which is the closest star to the Sun and part of the triple star system Alpha ...
, located 4.2 light years away, Tau Ceti e, 12 light years away, and Teegarden b, also located 12 light years away. The three planets are currently considered to be potentially habitable.
However, using the Sun as a gravitational lens would produce images with higher resolution when imaging potentially habitable exoplanets.
See also
*Gravitational lens
A gravitational lens is a distribution of matter (such as a cluster of galaxies) between a distant light source and an observer that is capable of bending the light from the source as the light travels toward the observer. This effect is known ...
* Gravitational microlensing
Gravitational microlensing is an astronomical phenomenon due to 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. Typically, astronomers ...
References
{{Reflist Atmospheric optical phenomena Observational astronomy Refraction