International Space Agencies – Missions and Discoveries

Dwarf Planets

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Dwarf Planets

Mains level : NA


  • As of today, there are officially five dwarf planets in our Solar System. Now, there is a claimant for a sixth dwarf planet.

Hygiea: New dwarf in the race

  • Using observations made through the European Space Organization’s SPHERE instrument at the Very Large Telescope (VLT), astronomers have now found Hygiea may possibly be a dwarf planet.
  • The most famous is Pluto, downgraded from the status of a planet in 2006. The other four, in order of size, are Eris, Makemake, Haumea and Ceres.
  • Called Hygiea, it has so far been taken to be an asteroid. It lies in the asteroid belt between Mars and Jupiter.
  • If it qualifies, Hygiea will be the smallest dwarf planet in the Solar System.

What makes a Hygiea dwarf?

  • The International Astronomical Union sets four criteria for a dwarf planet, and Hygiea already satisfies three — it orbits around the Sun, it is not a moon, and it has not cleared the neighbourhood around its orbit.
  • The fourth requirement is that it have enough mass that its own gravity pulls it into a roughly spherical shape.
  • According to the new study, VLT observations now show Hygiea satisfied that condition, too.
  • This is the first time astronomers have observed Hygiea in high resolution to study its surface and determine its shape and size.
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