International Space Agencies – Missions and Discoveries

Speculoos-3b: A New Earth-Sized Exoplanet Discovered


From UPSC perspective, the following things are important :

Prelims level: Red Dwarf Star, Speculoos-3b

Mains level: NA

Why in the News?

  • Astronomers have identified a new Earth-sized exoplanet, named Speculoos-3b, orbiting an ultracool red dwarf star.

Back2Basics: Red Dwarf Star

  • A red dwarf is the most common type of star in the Milky Way galaxy.
  • However, due to their low luminosity, individual red dwarfs cannot be easily observed.
  • Proxima Centauri, the star nearest to the Sun, is a red dwarf, as are fifty of the sixty nearest stars.
  • According to some estimates, red dwarfs make up three-quarters of the fusing stars in the Milky Way.

About Speculoos-3b

  • Speculoos-3b is an Earth-sized exoplanet recently discovered orbiting an ultracool dwarf star.
  • It was discovered by a team of astronomers led by Michael Gillon from the University of Liege in Belgium.
  • It is located approximately 55 light-years away from Earth.
  • Due to its short orbital period, Speculoos-3b receives almost ten times more energy per second than Earth does from the Sun.


  • Project Overview: The discovery was made under the SPECULOOS project, aimed at exploring exoplanets around ultra-cool dwarf stars.
  • The SPECULOOS Southern Observatory is a project carried out by the University of Liège (Belgium) and the Cavendish Laboratory in Cambridge (United Kingdom)

Astrophysical Significance of the Discovery

  • Prevalence of Ultracool Dwarfs: Ultracool dwarf stars, like the host of Speculoos-3b, constitute about 70% of all stars in our galaxy and are known for their longevity, surviving up to 100 billion years.
  • Importance for Life’s Potential: The extended lifespan of these stars provides a stable environment that could potentially support the development of life on orbiting planets.


[2015] The term ‘Goldilocks Zone’ is often seen in the news in the context of:

(a) the limits of habitable zone above the surface of the Earth

(b) regions inside the Earth where shale gas is available

(c) search for the Earth-like planets in outer space

(d) search for meteorites containing precious metals

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