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Goldilocks Zone

Published: 20th Jan, 2020

Goldilocks Zone

NASA has reported the discovery of an Earth-size planet, named TOI 700 d, orbiting its star in the “goldilocks zone”.


NASA has reported the discovery of an Earth-size planet, named TOI 700 d, orbiting its star in the “goldilocks zone”.


  • It is a habitable zone around a star where it is not too hot and not too cold for liquid water to exist on the surface of surrounding planets.
  • Our Earth is in the Sun’s Goldilocks zone, if Earth were the dwarf planet like Pluto is, all its water would freeze and if Earth were where Mercury is, all its water would boil off.
  • Life on Earth started in water, and water is a necessary ingredient for life. When scientists search for the possibility of alien life, any rocky exo-planet in the habitable zone of its star is an exciting find.
  • The newest such planet was found by NASA’s Transiting Exoplanet Survey Satellite (TESS) mission, which it launched in 2018.
  • Very few such Earth-size planets have been found so far, including some by NASA’s Kepler mission, and this one is the first such discovery by TESS.
  • The find was confirmed by the Spitzer Space Telescope, which sharpened the measurements that TESS had made, such as orbital period and size.

New discovered planet

  • TOI 700 d measures 20% larger than Earth. It orbits its star once every 37 days and receives an amount of energy that is equivalent to 86% of the energy that the Sun provides to Earth.
  • The star, TOI 700, is an “M dwarf” located just over 100 light-years away in the southern constellation Dorado, is roughly 40% of our Sun’s mass and size, and has about half its surface temperature.
  • TOI 700 d is the outermost planet, and the only one in the star’s habitable zone.

 Transiting Exoplanet Survey Satellite (TESS) mission:

  • The Transiting Exoplanet Survey Satellite (TESS) is a space telescope for NASA’s Explorers program, designed to search for exoplanets using the transit method in an area 400 times larger than that covered by the Kepler mission.
  • TESS launched on April 18, 2018, on a SpaceX Falcon 9 rocket.


NASA’s planet-hunter satellite TESS has discovered an Earth-sized planet named TOI 700 d within the habitable range of its star, which could allow the presence of liquid water which is a great discovery as there has a great hunt for the discovery of water on other planets.


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