Pluto was renamed a dwarf planet rather than a planet primarily due to its small size.

Size:
- Pluto is significantly smaller than the other planets in our solar system. It has a diameter of about 1,473 miles, which is much smaller than the Earth's diameter of about 7,917.5 miles. This small size led to the International Astronomical Union (IAU) reclassifying Pluto as a dwarf planet in 2006.

Classification Criteria:
- The IAU established three criteria for an object to be classified as a planet. These criteria include orbiting the sun, being spherical in shape, and clearing its orbit of other debris. While Pluto meets the first two criteria, it fails to meet the third criterion of clearing its orbit.

Orbit:
- Pluto's orbit overlaps with that of Neptune and is not cleared of other objects. This means that Pluto shares its orbit with other celestial bodies, unlike the eight recognized planets in our solar system that have cleared their orbits.

Reclassification:
- Due to its small size and failure to clear its orbit, the IAU decided to reclassify Pluto as a dwarf planet. This decision aimed to provide a clearer definition of what constitutes a planet in our solar system.
In conclusion, Pluto was renamed a dwarf planet rather than a planet primarily because of its small size and failure to meet all the criteria set forth by the IAU for planetary classification.

Why was Pluto renamed a dwarf planet rather than a planet?
Pluto was renamed a dwarf planet in 2006 due to several factors. The decision was made by the International Astronomical Union (IAU) after a lengthy debate and redefinition of the criteria for classifying celestial bodies.
Reasons for renaming Pluto as a dwarf planet:
- Small size: One of the main reasons for renaming Pluto was its small size. It was discovered that Pluto is significantly smaller than the other eight planets in our solar system. This led scientists to reconsider its classification as a full-fledged planet.
- Orbit: Another factor that played a role in reclassifying Pluto was its orbit. Pluto has a highly elliptical and inclined orbit, which is unlike the more circular and aligned orbits of the other planets. This unique orbit raised questions about its planetary status.
- Far distance: While distance alone was not the primary reason for Pluto's reclassification, its location in the outer regions of the solar system made it more susceptible to being reevaluated. The IAU wanted to establish a clear definition that could be applied to objects beyond Pluto as well.
- Cold temperature: Although Pluto's frigid temperatures were not the main factor in its reclassification, they were considered as part of the overall evaluation. Pluto's extremely cold environment, with temperatures averaging around -375 degrees Fahrenheit (-225 degrees Celsius), further highlighted its differences from the other planets.
In conclusion, Pluto's renaming as a dwarf planet was a result of its small size, unique orbit, far distance from the sun, and cold temperatures. These factors, among others, led to the redefinition of the criteria for classifying celestial bodies and ultimately the decision to classify Pluto as a dwarf planet.