Astronomy Practice Exam

Which of the following statements about Pluto is correct?

1. It is classified as a terrestrial planet

2. It is one of the gas giants

3. It is categorized as a dwarf planet

4. It has no orbital path

The correct answer is: It is categorized as a dwarf planet

Pluto is categorized as a dwarf planet, which is why this choice is correct. This classification was established by the International Astronomical Union (IAU) in 2006 when they defined the criteria that a celestial body must meet to be considered a planet. According to these criteria, a dwarf planet must orbit the Sun, be spherical in shape due to its own gravity, and not have cleared its orbital neighborhood of other debris. Pluto meets these criteria, but it does not clear its orbit of other objects, thus placing it in the dwarf planet category. Conversely, the classification of Pluto as a terrestrial planet is inaccurate. Terrestrial planets, like Earth and Mars, are primarily composed of rock and metal and are located closer to the Sun. Pluto is largely made of ice and rock and occupies a different region of the solar system (the Kuiper Belt). Pluto cannot be classified as one of the gas giants, which include Jupiter, Saturn, Uranus, and Neptune. Gas giants are characterized by their large sizes and gaseous compositions, lacking a well-defined solid surface. Pluto is significantly smaller and does not fit this category. Furthermore, the statement about Pluto having no orbital path is misleading. Pluto does have an orbital path; it takes