Which one of the following is a dwarf planet ?
Pluto
Understanding Dwarf Planets vs. Planets
To understand which of the options is a dwarf planet, it's important to know the definition of a planet and a dwarf planet as defined by the International Astronomical Union (IAU).
According to the IAU, a celestial body is considered a planet if it meets three criteria:
- It orbits the Sun.
- It has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape.
- It has cleared the neighbourhood around its orbit.
A dwarf planet meets the first two criteria but has not cleared the neighbourhood around its orbit.
Analyzing the Options
- Earth: Earth orbits the Sun, is massive enough to be round, and has cleared its orbital path. Therefore, Earth is a planet.
- Mercury: Mercury orbits the Sun, is massive enough to be round, and has cleared its orbital path. Therefore, Mercury is a planet.
- Venus: Venus orbits the Sun, is massive enough to be round, and has cleared its orbital path. Therefore, Venus is a planet.
- Pluto: Pluto orbits the Sun and is massive enough to be nearly round. However, it has not cleared the neighbourhood around its orbit; its orbit intersects with Neptune's, and it is part of the Kuiper Belt. For this reason, Pluto was reclassified as a dwarf planet in 2006.
Identifying the Dwarf Planet
Based on the criteria and the analysis of the options, the only celestial body listed that fits the definition of a dwarf planet is Pluto.
Here's a summary:
| Celestial Body | Orbits the Sun? | Nearly Round? | Cleared Orbit? | Classification |
|---|---|---|---|---|
| Earth | Yes | Yes | Yes | Planet |
| Mercury | Yes | Yes | Yes | Planet |
| Venus | Yes | Yes | Yes | Planet |
| Pluto | Yes | Yes | No | Dwarf Planet |
Thus, among the given options, Pluto is the dwarf planet.
Important Questions from Origin and evolution of Universe Solar system
- Despite its greater distance from the Sun compared to Mercury, Venus maintains the highest surface temperature of any planet in our solar system. Which of the following is the primary reason for Venus's extreme heat?
What was the name of the mega-ocean that surrounded the single continental mass before the continental drift as described by Alfred Wegener?
A huge collection of gas, dust and billions of stars is called a:
The Greenwich Mean Time is the local time at :
The force exerted by rotation of the earth is known as:
