Pluto Day

Celebrated on 02/18/2026

Quick Fact

Pluto Day is celebrated on February 18th, marking the anniversary of its discovery in 1930 by Clyde Tombaugh. Despite its reclassification as a dwarf planet in 2006, Pluto remains a beloved celestial body and the subject of ongoing scientific study.

Origins and Establishment of Pluto Day

Pluto Day was established to commemorate the discovery of Pluto by American astronomer Clyde Tombaugh on February 18, 1930, at the Lowell Observatory in Flagstaff, Arizona. The holiday was informally created by astronomy enthusiasts and educators to celebrate this milestone in solar system exploration. Tombaugh discovered Pluto through a painstaking process of comparing photographic plates, and the new planet was named by an 11-year-old British schoolgirl, Venetia Burney, after the Roman god of the underworld.

Evolution and Modern Commemoration

For decades, Pluto was celebrated as the ninth planet, but its reclassification as a dwarf planet by the International Astronomical Union in 2006 sparked debate and renewed public interest. Today, Pluto Day is observed by planetariums, science museums, and space agencies through educational events, telescope viewings, and social media campaigns. The New Horizons mission, which flew by Pluto in 2015, revitalized enthusiasm, providing stunning images and data that transformed our understanding of this distant world.

Facts & General Observations

• Pluto takes about 248 Earth years to orbit the Sun, meaning it has completed less than one full orbit since its discovery.
• Despite being reclassified, Pluto has five known moons: Charon, Styx, Nix, Kerberos, and Hydra.
• The New Horizons spacecraft traveled over 3 billion miles to reach Pluto, capturing the first close-up images of its surface.

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