Which one of the following is a dwarf planet ?

Question

Accepted Answer

Pluto is classified as a dwarf planet, which is why Option 4 is the correct answer. The International Astronomical Union (IAU) redefined the criteria for planet classification in 2006, leading to Pluto's reclassification from a planet to a dwarf planet. According to the IAU, a dwarf planet is a celestial body that orbits the Sun, has sufficient mass for its self-gravity to overcome rigid body forces and achieve a nearly round shape, but has not cleared its neighboring region of other objects. Pluto meets these criteria, as it orbits the Sun and is spherical in shape, but it shares its orbital space with other objects in the Kuiper Belt.

Now, let's examine why the other options are incorrect:

1. Earth: Earth is not a dwarf planet; it is classified as a terrestrial planet. It meets all the criteria for being a planet, including having cleared its orbit of other debris.

2. Mercury: Mercury is also a terrestrial planet, not a dwarf planet. It orbits the Sun and has cleared its orbital path, fulfilling the criteria for being a planet.

3. Venus: Venus is another terrestrial planet. Like Earth and Mercury, it has cleared its orbit and meets the criteria for being classified as a planet.

In summary, Pluto is the only option among the given choices that fits the definition of a dwarf planet, making Option 4 the correct answer.