Pluto, the dwarf planet that was controversially demoted from full planetary status in 2006, has a fascinating history behind its name and discovery. While many may know that Pluto was named after the Roman god of the underworld, some may be surprised to learn that it was almost named after a much more modern icon – Mickey Mouse.
The Discovery of Pluto
Pluto was discovered on February 18, 1930 by American astronomer Clyde Tombaugh at the Lowell Observatory in Flagstaff, Arizona. The observatory had been actively searching for a “Planet X” beyond Neptune since the early 1900s, as mathematical calculations suggested there should be an additional planet in the outer solar system exerting gravitational influence on the orbits of Uranus and Neptune.
Tombaugh was tasked with systematically comparing photographic plates of the night sky to look for any moving objects, indicating a planetary body. After a year of searching, Tombaugh finally discovered a faint point of light that shifted positions between photos taken a few nights apart. This proved the existence of what would finally be named Pluto.
The Naming Process
The discovery of Pluto was announced on March 13, 1930, but it would take another three weeks before Tombaugh’s newly discovered object received an official name. This was partially due to the fact that the naming process sparked heated debates between astronomers at the Lowell Observatory and overseas.
Percival Lowell, the astronomer who founded the Lowell Observatory, had theorized that Planet X should lie beyond Neptune. He suggested several potential names for the hypothesized planet, including Minerva and Cronus. Other astronomers proposed the name Zeus for the new planet.
However, the Lowell Observatory ultimately decided to leave the naming up to 23-year-old Tombaugh. With the help of observatory director Vesto Slipher’s young son and niece, Tombaugh settled on Pluto. This was partly in honor of Percival Lowell’s initials (“PL”) and also for the dark, cold, and faraway nature of the Roman god Pluto.
How Mickey Mouse Almost Entered the Picture
While Tombaugh and Lowell Observatory eventually settled on Pluto, Disney apparently had other ideas. According to some reports, Disney was heavily lobbying for the new planet to be named after Mickey Mouse’s pet dog Pluto.
1930 was just a few years after the creation of Mickey Mouse and the rise of Disney’s popular cartoon character. The potential naming of the newly discovered planet after Mickey’s canine companion could have been a publicity move to capitalize on the discovery and draw further attention to Disney’s beloved icon.
However, the international astronomy community pushed back against Disney’s supposed efforts. Given the importance of the first planet discovered in several decades, most astronomers felt that naming it after a cartoon dog would be frivolous and disrespectful to science.
While Mickey Mouse’s Pluto certainly became iconic in his own right, astronomers were intent on giving the dwarf planet a more serious name befitting of its significance. Any behind-the-scenes efforts by Disney to hijack the naming process were ultimately unsuccessful.
Pluto’s Changing Status
For over 75 years after its discovery, Pluto enjoyed planetary status alongside the other eight planets in our solar system. But in 2006, its categorization suddenly changed.
That year, astronomers approved a new distinct definition for planets, requiring them to meet certain criteria regarding orbital characteristics and having sufficient mass to assume hydrostatic equilibrium (a nearly round shape). According to this new definition, Pluto was reclassified as a “dwarf planet” along with other similar-sized objects beyond Neptune’s orbit.
While no longer considered an official planet, Pluto is still recognized as one of the largest known trans-Neptunian objects and an integral part of our outer solar system. It maintains iconic cultural status despite its reclassification.
Pluto’s demotion sparked substantial controversy, with some arguing it should have remained categorized as a planet out of respect for historical tradition. But the improved understanding of our solar system’s structure necessitated a more scientifically rigorous definition for planets. Over a decade later, Pluto’s dwarf planet status has generally become accepted within the astronomy community.
Key Facts About Pluto
Here are some key facts about the dwarf planet Pluto:
- Orbital period: 248 years
- Mean radius: 715 miles (1,151 km)
- Number of moons: 5 (Charon, Nix, Hydra, Kerberos and Styx)
- Surface composition: 98% nitrogen ice, 1.5% methane ice, 0.5% carbon monoxide ice
- Distance from the Sun: Over 3.6 billion miles (5.8 billion km)
- Length of day: 153 hours
- Discovery year: 1930
- Discovered by: Clyde Tombaugh at Lowell Observatory
Some key milestones in Pluto’s history are summarized in this table:
| Year | Event |
|---|---|
| 1905 | Percival Lowell initiates search for Planet X |
| 1930 | Clyde Tombaugh discovers Pluto at Lowell Observatory |
| 1930 | Pluto’s name formally adopted |
| 1978 | Pluto’s moon Charon discovered |
| 2006 | Pluto reclassified as a dwarf planet |
| 2015 | NASA’s New Horizons performs flyby of Pluto |
Conclusion
While Pluto may not have become Mickey Mouse’s planet as Disney supposedly desired, it has retained its place of prominence within our solar system and our cultural imagination. Its unexpected demotion sparked constructive debate about how we categorize planets versus dwarf planets. And NASA’s epic New Horizons flyby offered our first close-up view of this mysterious, frozen world.
Pluto’s history is a reminder that science is an evolving process, where our understanding is refined over time by new data and improved theories. Regardless of its classification, the dwarf planet Pluto will continue to inspire wonder about the outer reaches of our solar neighborhood.