Every year on February 18, Pluto Day is celebrated to commemorate the anniversary of the discovery of Pluto in 1930. The planet was discovered by American astronomer Clyde W. Tombaugh.
The discovery of Pluto was a historic moment that opened up the door for humanity to explore even further into outer space and understand more about our universe. Clyde discovered Pluto at the Lowell Observatory in Flagstaff, Arizona just 84 years after the discovery of Neptune. He spent months comparing photos of the night sky, looking for a moving object that hinted at a distant planet. His careful observation led to the confirmation of a new celestial body, later named Pluto.
Significance of Pluto Day
The discovery proved to be a major stepping stone for humanity’s understanding of the universe. Every year, Pluto Day serves as an inspirational reminder to never stop learning and exploring new frontiers in science and technology. The worldwide celebration of Pluto Day is indicative of how global collaboration and cooperation can lead to amazing research results. It shows that we can achieve astronomically great things together with dedication, enthusiasm, and support from all corners of the globe.
History of Pluto Day
Although Pluto was discovered in 1930, the story of its discovery started in 1840 after French astronomer Urbain Le Verrier sensed that there was a planet outside of Uranus due to irregularities in its orbit. His intuition led him to develop mathematical calculations to explain the discrepancies of Uranus’s orbit in relation to the laws of planetary motion and gravity, which led to the eventual discovery of Neptune.
After Neptune was discovered, an event that is widely regarded as a validation of a subset of the astronomy practice called celestial mechanics. It was then realized that there was yet another planet disturbing Uranus’s orbit since the irregularity in its orbit continued. This then led to the search for Pluto, initially called Planet X, being headed by Percival Lowell, whose death would later see the search for Pluto passed to Clyde Tombaugh, who eventually discovered it.
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The name “Pluto” was suggested by an 11-year-old English girl named Venetia Burney, who thought it fit well with the names of other mythological Roman gods used for planets.
For decades, Pluto was known as the ninth planet in our solar system. However, in 2006, the International Astronomical Union (IAU) reclassified it as a dwarf planet, due to its small size and irregular orbit. Despite the change, Pluto remains a beloved symbol of exploration and discovery.
5 facts about Pluto
Pluto is about 3.7 billion miles away from the Sun.
A year on Pluto lasts 248 Earth years, meaning it hasn’t completed a single orbit since its discovery.
Pluto has five moons, the largest being Charon, which is almost half its size.
The surface of Pluto is covered with frozen nitrogen, methane, and carbon monoxide.
NASA’s New Horizons spacecraft flew past Pluto in 2015, giving us the first close-up images of its icy mountains and heart-shaped region.
How to Celebrate Pluto Day 2026
There are many fun and meaningful ways to mark Pluto Day:
Discover more about Pluto – Dive into books, articles, or documentaries about its discovery and space exploration missions such as NASA’s New Horizons.
Explore the Night Sky – Head to a nearby observatory or use a telescope at home to observe planets, stars and constellations.
Try a Space-inspired activity – Build a solar system model, draw Pluto’s orbit, or even prepare galaxy themed treats.
Spread the word – Share interesting Pluto trivia on social media using the hashtag #PlutoDay.
Spark interest in space science – Motivate friends and family to explore astronomy and learn about mysteries of the universe.
