Question

select the correct answer.

pluto has a shape that is nearly round, and it orbits the sun. it has five known moons. why is it called a dwarf planet and not a planet?

• it is too far from the sun.
• its orbit is not cleared of like-sized or larger objects.
• it is not large enough in size.
• it does not have rings.

Explanation:

Define the criteria for a planet

According to the International Astronomical Union (IAU), a celestial body must meet three criteria to be classified as a planet:

1. It must orbit the Sun.
2. It must have sufficient mass to assume a nearly round shape (hydrostatic equilibrium).
3. It must have "cleared the neighborhood" around its orbit of other objects.

Evaluate Pluto against the criteria

Using the Dwarf Planets knowledge point

• Pluto orbits the Sun and is nearly round, satisfying the first two criteria.
• However, Pluto shares its orbital zone in the Kuiper Belt with many other similar-sized icy bodies.
• Therefore, Pluto has not cleared its orbital neighborhood, which is why it is classified as a dwarf planet.

Answer:

• (A) It is too far from the Sun.
• (B) Its orbit is not cleared of like-sized or larger objects. (Correct answer)
• (C) It is not large enough in size.
• (D) It does not have rings.