Understanding Dwarf Planets

Understanding Dwarf Planets

Astronomy Discussion

Dwarf planets continue to incite debate and intrigue as scientists continue to discover more of these objects in space. Since 1930, when Pluto was added as a planet, the debate over what defines a planet began. The debate ended in 2006 when the International Astronomical Union created a new classification of celestial bodies to define these objects. The term dwarf planet was chosen because it described the bodies as being more developed than asteroids possessing inferior gravitational fields to that of planets. These dwarf planets have independent orbits with the sun but still inhabit the regions of space where asteroids and other objects are found.

Understanding Dwarf Planets

By NASA / Johns Hopkins University Applied Physics Laboratory / Southwest Research Institute - Public Domain

The best known Dwarf planet is Pluto. This mysterious dwarf planet was the only dwarf once considered a planet and was reassigned as a dwarf planet (, 2012). This demotion actually signaled a new era of discovery in which scientists have begun discovering more of these objects. Because Pluto is one of the primary objects used in defining a dwarf planet, the more that is discovered about this object the better science can judge other dwarf planets and celestial bodies.

Surprisingly, very little is still known about Pluto due to the large distance between the dwarf and earth. What is known about Pluto is relatively recent in discovery due to the Hubble Telescope. Some of the assumptions and estimates believed to be true of this dwarf planet include:

· Earth’s moon is larger than Pluto.
· Pluto is reddish-brown in color.
· Pluto’s surface is approximately minus 375 degrees F (minus 225 degrees C).
· Pluto’s moon, Charon is more than half the size of the planet.
· The sun appears as a bright star from Pluto.
· Pluto’s atmosphere contains traces of methane, nitrogen, and carbon dioxide.
· Pluto was possibly a moon of Neptune before escaping into its orbit of the sun.
· Pluto’s irregular orbit, takes it closer to the sun than Neptune at times.
· Pluto has three moons (, 2012).

What is not known is the state of Pluto’s magnetic field and atmospheric conditions. The actual size of the dwarf is also questionable due to its distance from the earth and its high elevated atmosphere which interferes with measuring the size of the surface. Despite the fact that the existence of Pluto has been known since 1930 more has been discovered about other dwarf planets because of the closer distance with the earth.

Ceres, for example, is a dwarf planet that resides in an orbit between Mars and Jupiter. This dwarf is believed to have a rock core with an ice mantle. The dwarf is approximately 950 kilometers in diameter and is close enough to earth that probe expeditions are more practical and less time consuming. The most intriguing quality of Ceres is that there is a good possibility that beneath the ice mantle of the dwarf there could be an ocean. This greatly increases the chances of finding extraterrestrial life (Pitjeva, 2004). The idea of dwarf planets and non-planet objects holding life has in recent years become a greater possibility than it actually appearing on the planets within the solar system. This makes these celestial bodies ever more intriguing.

Currently, there are two missions underway that will investigate dwarf planets. The Dawn mission is currently underway and is already providing data about asteroids and dwarf planets, investigating Ceres and Vesta (large protoplanets) hoping to learn more about the evolution of planets in the solar system (NASA, 2012).

Dawn has already finished mapping Vesta and is currently underway to Ceres. The detailed data retrieved from Dawn will be able to answer many questions concerning Ceres such as actual orbital trajectory and whether the dwarf has magnetic fields and its more exact atmospheric conditions. Dawn is expected to arrive at Ceres in 2015.

Even more intriguing is the New Horizons mission which is also estimated to arrive in 2015 to explore Pluto. The New Horizons mission will take 10 years to complete and in 2015 the probe will begin exploring Pluto and the outer edge of our solar system (NASA, 2012). New Horizons has already completed investigations of Mars, Jupiter, Uranus, and many of the moons orbiting these bodies.

In the time that it has taken New Horizons to reach Pluto, scientists have learned that there may be hundreds of similar dwarf planets rotating the sun. The discovery has already caused NASA to consider alternative plans or maneuvering the probe in order to avoid collisions if there are more celestial bodies in the area of Pluto (NASA, 2012).

The New Horizon’s mission will take the probe deep into what is known as the Kuiper-belt after exploring Pluto. The Kuiper-belt may contain as many as 100,000 objects consisting of dwarf planets and ice formations and asteroids (NASA, 2012). The New Horizon’s mission will redefine how the solar system is shaped and how it is laid out with planets and objects.

The Dawn and New Horizons missions are extremely important for assessing the size and shape of the solar system. The discovery of more dwarf planets such as Pluton will provide scientists with more evidence of how the solar system was formed and its current motions and size. These missions will also help scientists assess future missions by providing information as to which planets and objects should be prioritized for exploration. More importantly, the more information derived from these missions provides scientists with answers as to whether there is a possibility of finding new life beyond earth and resources which could provide humans with answers to current resource restrictions.

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NASA. (2012). Mission. Retrieved from

NASA. (2012). Kuiper belt & oort cloud: Overview. Retrieved from

NASA. (2012). Latest news. Retrieved from

Pitjeva, E. V. (2004, August 9). High-precision ephemerides of planets — epm and determination of some astronomical constants. (2012). Pluto, the ninth planet that was a dwarf. Retrieved from


Triola Vincent. Wed, Jan 06, 2021. Understanding Dwarf Planets Retrieved from

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