The Exploration of Dwarf Planets

‘Why did Mickey Mouse take a trip into space?’

‘He wanted to find Pluto!’

Figure 1: Mickey mouse and Pluto (Heritage Auctions, 2017)

Here. This exact joke has been a debate going on for more than a decade. It's been 18 years since Pluto's celestial status was called into question—yet the matter seems far from settled… Have you ever wondered whether dwarf planets are actually classified as “planets”? Have you ever thought about what they looked like?  

Dwarf planets like Ceres, Pluto, Haumea, Makemake, and Eris may be diminutive in size, but they hold significant scientific importance. 

Since the reclassification of Pluto as a dwarf planet in 2006 by the International Astronomical Union (IAU), scientific interest in these distant worlds has grown significantly. Exploring these planets provided crucial insights into the formation and evolution of the solar system (Iau.org, 2025).

What Defines a Dwarf Planet?

Figure 2: Dwarf Planets in the Solar System (Tate, 2012)

According to the International Astronomical Union, a dwarf planet must meet three criteria. Unlike moons, these planets directly orbit the Sun. Their shape is nearly round due to gravitational forces and unlike major planets, dwarf planets share their orbits with other objects (NASA, 2023).

Currently, the IAU recognizes five dwarf planets: Pluto, Eris, Haumea, Makemake, and Ceres. However, there are dozens more based on our understanding of the Kuiper Belt and beyond.  

Key Dwarf Planets and Their Exploration

Figure 3: New Horizons (NASA, 2024)

Pluto, once considered the ninth planet, remains the most well-studied dwarf planet from NASA's “New Horizons” mission. In 2015, it discovered Pluto's surprisingly active surface with nitrogen glaciers and floating mountains, while still having possible cryovolcanoes and a subsurface ocean (Dooling, 2009).  

These findings suggest that the dwarf planet Pluto is far more geologically active than humankind initially thought. 

Why Explore Dwarf Planets?

Figure 4: Surface of Dwarf Planets (Hauck, S.A. and Sizemore, H, 2019)

Dwarf planets are remnants of the early solar system, preserving clues about planetary accretion. Icy dwarf planets like Pluto and Ceres show us the building blocks of life. Not only does studying these bodies help engineers design missions, it allows us to explore even more distant targets, such as interstellar objects like ‘Oumuamua (University of Chicago News, 2023).

Future Missions and Exploration

Figure 5: Future explorations (NASA, 2014)

While New Horizons and other space projects have provided data that allowed us to further understand outer space, many questions remain. Proposed future missions include:  Pluto orbiter, to study its atmosphere and geology long-term, Kuiper Belt flybys, to explore Eris, Haumea, or Makemake and sample returns from Ceres to analyze its water and organic content.

However, challenges such as extreme distances, long mission durations, and high costs must be overcome.  

Conclusion

The exploration of dwarf planets has revolutionized our understanding of the solar system, revealing dynamic, complex worlds rather than inert frozen rocks. As technology advances, future missions will uncover even more about these enigmatic bodies, potentially reshaping our knowledge of planetary science and astrobiology. Dwarf planets, once overlooked, now stand at the forefront of astronomical discovery.  

Works Cited

Dooling, D. (2009). New Horizons | Discoveries & Facts. [online] Encyclopedia Britannica. Available at: https://www.britannica.com/topic/New-Horizons [Accessed 3 Apr. 2025].

Heritage Auctions. (2017). Mickey Mouse and Pluto Fan Card Print (Walt Disney, c. 1930s).... | Lot #97235 | Heritage Auctions. [online] Available at: https://comics.ha.com/itm/memorabilia/comic-related/mickey-mouse-and-pluto-fan-card-print-walt-disney-c-1930s-/a/7148-97235.s [Accessed 3 Apr. 2025].

Hauck, S.A. and Sizemore, H. (2019). Ceres: Evolution of the Asteroid Belt’s Icy Giant. [online] Eos. Available at: https://eos.org/editors-vox/ceres-evolution-of-the-asteroid-belts-icy-giant [Accessed 3 Apr. 2025].

Iau.org. (2025). Home. [online] Available at: https://www.iau.org/ [Accessed 3 Apr. 2025].

Nasa.gov. (2024). Mars Exploration: Science Goals - NASA Science. [online] Available at: https://science.nasa.gov/planetary-science/programs/mars-exploration/science-goals/ 

NASA. (2014). The Future of Space Exploration Starts on Earth - NASA. [online] Available at: https://www.nasa.gov/image-article/future-of-space-exploration-starts-earth/ [Accessed 3 Apr. 2025].

NASA (2023). Pluto & Dwarf Planets. [online] NASA Science. Available at: https://science.nasa.gov/dwarf-planets/ [Accessed 3 Apr. 2025].

Rmg.co.uk. (2025). The dwarf planets: Pluto, Ceres, Haumea, Makemake and Eris. [online] Available at: https://www.rmg.co.uk/stories/topics/dwarf-planets-pluto-ceres-haumea-makemake-eris [Accessed 3 Apr. 2025].

Tate, K. (2012). Dwarf Planets of Our Solar System (Infographic). [online] Space.com. Available at: https://www.space.com/18584-dwarf-planets-solar-system-infographic.html [Accessed 3 Apr. 2025].

University of Chicago News. (2023). A surprisingly simple explanation for interstellar visitor ‘Oumuamua’s weird orbit. [online] Available at: https://news.uchicago.edu/story/surprisingly-simple-explanation-interstellar-visitor-oumuamuas-weird-orbit [Accessed 3 Apr. 2025].

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