2005

January

• January 5: Michael Brown discovers Eris.
• January 12: The Deep Impact spacecraft is launched.
• January 14: The Huygens part of Cassini-Huygens spacecraft lands on Titan.
• January 26: Haumea‘s moon Hi’iaka is discovered.

March

• March 31: Makemake is discovered.

June

• June 15: Pluto‘s moons Hydra and Nix are discovered.
• June 30: Haumea‘s moon Namaka is discovered.

July

• July 4: Deep Impact makes a flyby of the comet Tempel 1 and sends a lander onto it’s surface.
• July 27: José Luis Ortiz Moreno claims he discovered Haumea.

August

• August 2: MESSENGER makes a flyby of Earth.

September

• September 10: Eris’s moon Dysnomia is discovered.

November

• November 13: Orcus‘s moon Vanth is discovered.