Pluto

Definition

Pluto is a dwarf planet located in the outer reaches of the Solar System. It was once considered the ninth planet from the Sun but was reclassified as a dwarf planet in 2006. Pluto's unique characteristics and its place in the Solar System make it an important object of study in various astronomical topics.

5 Must Know Facts For Your Next Test

1. Pluto was discovered in 1930 by American astronomer Clyde Tombaugh, making it the first object discovered in the modern era of astronomy.
2. Pluto is the smallest and most distant dwarf planet in the Solar System, with a diameter of approximately 1,430 miles (2,370 kilometers).
3. Pluto has a highly elliptical and inclined orbit, taking 248 years to complete one revolution around the Sun.
4. Pluto's composition is primarily ice and rock, with a thin atmosphere of nitrogen, methane, and carbon monoxide when near the Sun.
5. The Pluto-Charon system is considered a binary system, as the two bodies orbit a common center of mass between them.

Review Questions

• Explain Pluto's reclassification from a planet to a dwarf planet, and how this change in status affects our understanding of the Solar System.
  • In 2006, the International Astronomical Union (IAU) established a new definition for a planet, which Pluto did not meet. Pluto was reclassified as a dwarf planet because it has not cleared the area around its orbit of other objects, as required for a full-fledged planet. This change in Pluto's status has led to a better understanding of the diverse population of small bodies in the outer Solar System, particularly in the Kuiper Belt region where Pluto resides. The reclassification has also prompted a re-evaluation of the criteria used to define planets, highlighting the complexity of categorizing celestial objects and the ongoing nature of scientific discovery.
• Describe the unique characteristics of Pluto's orbit and how they contribute to our understanding of the origin and evolution of the Solar System.
  • Pluto's highly elliptical and inclined orbit, with a period of 248 years, sets it apart from the more circular and coplanar orbits of the major planets. This unusual orbital configuration suggests that Pluto may have formed differently from the other planets, possibly as a member of the Kuiper Belt population. The study of Pluto's orbit and its interactions with other Kuiper Belt objects provides valuable insights into the early dynamics and evolution of the outer Solar System, including the potential migration of the giant planets and the clearing of material from the Kuiper Belt region.
• Analyze the significance of the Pluto-Charon binary system and how it informs our understanding of the formation and evolution of dwarf planets and their moons.
  • The Pluto-Charon binary system is unique in the Solar System, as the two bodies orbit a common center of mass between them. This feature suggests that Pluto and Charon likely formed from the same parent body, rather than Charon being captured by Pluto's gravity. The study of the Pluto-Charon system provides insights into the processes of dwarf planet formation, including the role of collisions and tidal forces in shaping the characteristics of these small bodies and their moons. Additionally, the Pluto-Charon system serves as a model for understanding the formation and evolution of other binary systems in the Kuiper Belt, which can help scientists piece together the broader story of how the outer Solar System took shape.

Related terms

Kuiper Belt: The Kuiper Belt is a region of the Solar System beyond the orbit of Neptune, containing numerous icy objects, including Pluto and other dwarf planets.

Charon: Charon is Pluto's largest moon, and the two bodies are often considered a binary system due to their similar sizes and shared center of mass.

Dwarf Planet: A dwarf planet is a celestial body that orbits the Sun, is large enough to be rounded by its own gravity, but has not cleared the area around its orbit of other objects.