Pluto, once known as the ninth planet of our solar system, continues to captivate us with its icy mysteries and distant travels.
As a dwarf planet, Pluto may be smaller than Earth’s moon, but it holds no less intrigue for young minds eager to explore the cosmos.
For many years, it was counted among the planets of our solar system until a reclassification in 2006 placed it into the realm of dwarf planets.
Our journey through the solar system would not be complete without visiting this remote world, which orbits, on average, 3.7 billion miles away from the Sun.
Despite its size, Pluto offers a vast array of features from mountains, valleys, and craters to a composition thought to include water ice.
Its surface temperatures, however, are unimaginably cold, averaging between -375 and -400 degrees Fahrenheit.
Understanding Pluto helps us appreciate the complexity and diversity within our solar system.
For instance, Pluto’s largest moon, Charon, is about half its size—a unique feature when compared to other celestial bodies and their satellites.
This pair, along with Pluto’s other moons, provides a fantastic case study in the gravitational dance that takes place all around us in space.
How Was Pluto First Discovered?
The discovery of Pluto was a significant moment in astronomical history, marking the identification of what was then considered the ninth planet in our solar system.
This achievement was the culmination of years of searching and the dedicated work of several scientists, including Clyde Tombaugh at the Flagstaff observatory.
Evidence of a possible ninth planet was first noted due to unexpected deviations in the orbits of Uranus and Neptune.
Astronomers theorized the existence of a ‘Planet X’ that could be influencing their paths.
The search for this mysterious body spanned many years and involved numerous observatories across the United States.
Clyde Tombaugh’s Contribution
Our knowledge of Pluto dramatically advanced thanks to Clyde Tombaugh, an American astronomer.
On February 18, 1930, while working at the Lowell Observatory in Arizona, Tombaugh discovered Pluto.
His meticulous examination of photographic plates, which captured small shifts in the position of a celestial body when compared to stars, led to this groundbreaking finding.
Who Named The Planet Pluto?
The name ‘Pluto’ was proposed by Venetia Burney, an eleven-year-old schoolgirl from Oxford, England.
The name, which refers to the Roman god of the underworld, was fitting for a planet that resided in the dark, remote regions of the solar system.
It also honored the legacy of Percival Lowell, as ‘PL’ are his initials.
Why Was Pluto Reclassified As A Dwarf Planet?
In 2006, our understanding of what constitutes a planet was revised.
The International Astronomical Union reclassified Pluto as a ‘dwarf planet’ due to the realization that it did not meet all the criteria previously established for planets.
This was a controversial decision, but it led to a new perspective on how we define objects in our solar system.
NASA’s New Horizons mission further expanded our knowledge by gathering more data on Pluto as it flew by the dwarf planet in 2015.
This mission revealed more details about Pluto’s surface and its moons, providing astronomers and the public alike with new insights into this distant world.
Physical Characteristics of Pluto
1. Orbit and Rotation
Pluto’s orbit is highly elliptical, taking it on a journey closer to the Sun than Neptune at its perihelion and farther away at its aphelion.
A Plutonian year—the time it takes to complete one orbit around the Sun—is approximately 248 Earth years.
Its rotation period or day spans about 6.4 Earth days. Pluto’s orbit is inclined relative to the primary plane of the solar system, which contributes to its unique orbital characteristics.
2. Pluto’s Moons
Pluto has five known moons, with Charon being the largest.
Charon is about half the diameter of Pluto, making them a binary system since they orbit a common center of gravity.
The other four moons—Styx, Nix, Kerberos, and Hydra—are much smaller but play a role in the Pluto-Charon system’s dynamics.
- Charon: Radius of 606 kilometers
- Styx: Irregular shape, approximately 7x5x4 kilometers
- Nix: Measured at 50 kilometers in length
- Kerberos: Smaller and fainter than the other moons
- Hydra: Second-largest moon after Charon with elongated shape
3. Geology and Surface Features
Pluto’s surface is covered with ice and rock, displaying a varied landscape that includes sprawling valleys, vast plains, large craters, and possibly glaciers.
Its most prominent geological features may be the enormous mountains that tower as high as 3,500 meters.
The surface temperature, being so far from the Sun, can plummet as low as -375 degrees Fahrenheit (-225 degrees Celsius).
This extreme cold causes the nitrogen, methane, and carbon monoxide ices to behave almost like rock.
4. Pluto’s Atmosphere
Although it has an atmosphere, it’s mostly composed of nitrogen with traces of methane and other gases.
This thin atmosphere expands as Pluto comes closer to the Sun and freezes onto the surface as it moves away.
Due to its low gravity, Pluto’s atmosphere is quite extended but escapes gradually into space.
The temperature of the atmosphere is about 70 Kelvin (-333.07 degrees Fahrenheit, -203.15 degrees Celsius), and it contributes to a slight and temporary greenhouse effect.
Where Does Pluto Lie In The Solar System?
Pluto stands as a unique and distant world, nestled in the outer regions of our solar system.
As a dwarf planet, it offers invaluable insights into the composition and dynamics of the Kuiper Belt, as well as its intriguing orbital dance with Neptune.
Kuiper Belt and Trans-Neptunian Objects
Pluto is a prominent member of the Kuiper Belt, a vast ring of icy bodies orbiting beyond Neptune.
This region is home to a variety of Kuiper Belt Objects (KBOs), which include dwarf planets like Pluto and Eris, as well as smaller celestial bodies.
Pluto’s presence in this belt helps us understand more about these far-flung remnants of our solar system’s formation.
With a surface composed largely of water ice and a rocky core, Pluto’s structure is representative of many large KBOs.
The Hubble Space Telescope has played a crucial role in studying these distant objects, helping us classify a subgroup known as plutoids which, similar to Pluto, orbit beyond Neptune and have enough mass to maintain a near-spherical shape.
Despite being over 5 billion kilometers away, observations from Earth have revealed that Pluto also has a tenuous atmosphere, primarily nitrogen with traces of methane and carbon monoxide.
Pluto’s Interaction with Neptune
An interesting aspect of Pluto is its orbital relationship with Neptune; they are in a 3:2 resonance, meaning Pluto orbits the Sun twice for every three Neptune orbits.
Although their paths cross, the resonance ensures they never collide. This gravitational interaction is a fascinating example of the precise celestial mechanics that govern planetary movements within our solar system.
Neptune’s massive presence and gravitational pull have influenced Pluto’s trajectory, leading to a highly inclined and elliptical orbit.
Although part of the Kuiper Belt, Pluto’s interaction with Neptune distinguishes it from typical KBOs.
Unique features such as Tombaugh Regio, a large, heart-shaped region on Pluto’s surface, are of significant interest as we explore how Neptune and other factors may have shaped the dwarf planet’s geological history.
Missions To Pluto
The most notable mission to Pluto is NASA’s New Horizons spacecraft, which we launched in 2006 with the aim to shed light on the outer reaches of our solar system.
After a nine-year journey, New Horizons performed a historic flyby in 2015, offering unprecedented close-up images and data on Pluto and its moons.
This mission marked the first time we had visited Pluto, allowing us to observe its diverse geography and complex atmosphere.
Key findings from New Horizons underscored Pluto’s status as an active dwarf planet, with flowing nitrogen ice glaciers and a possible subsurface ocean.
The Hubble Space Telescope has also been instrumental in studying Pluto from afar, helping us identify its four smaller moons and providing ongoing data on the dwarf planet’s orbit and atmosphere.
Ongoing Research and Future Exploration Of Pluto
Our study of Pluto goes far beyond the initial flyby. Ongoing analysis of New Horizons data continues to enhance our understanding of this dwarf planet.
For instance, we’re discovering more about Pluto’s intriguing interactions with the solar wind and its complex seasonal changes.
Scientists in the astronomical community, utilizing telescopes like Hubble, and soon the James Webb Space Telescope, continue to observe Pluto and similar icy objects in the Kuiper Belt, such as Makemake.
These observations aim to compare Pluto’s geology and composition with these other objects, giving us a more comprehensive understanding of the outer solar system.
Frequently Asked Questions About Pluto
Why was Pluto reclassified as a dwarf planet?
Pluto was reclassified as a dwarf planet in 2006 by the International Astronomical Union because it does not clear its orbit of other debris and objects, a criterion required for full-fledged planets.
What materials make up the composition of Pluto?
Our understanding is that Pluto consists of a mixture of rock and ice, with about one third of its mass being water ice.
How many moons are in orbit around Pluto, and can you name them?
There are five moons in orbit around Pluto: Charon, Hydra, Nix, Kerberos, and Styx, with Charon being the largest and closest to Pluto.
What is the distance between Pluto and the Sun?
The distance between Pluto and the Sun varies due to its elliptical orbit, averaging about 3.67 billion miles (5.9 billion kilometers).
When was Pluto first discovered and who discovered it?
Pluto was first discovered in 1930 by American astronomer Clyde Tombaugh at the Lowell Observatory in Arizona.
What color is the surface of Pluto as seen from space?
Viewed from space, Pluto’s surface appears to range from light brown to a reddish color, with contrasting bright and dark regions.
