Why is Pluto not a full planet under the IAU definition?

It has not cleared its orbit of other objects

Who suggested the name Pluto?

An 11-year-old girl, Venetia Burney

Dwarf Planets Quiz – How Much Do You Really Know?

This dwarf planets quiz covers Pluto, Ceres, Eris, Haumea and Makemake, the 2006 definition of a planet, New Horizons and the Kuiper Belt. Ten questions test how much you really know about the solar system's smaller worlds.

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🎯 Daily Trivia Challenge • 🧠 10 Questions • ⏱️ 150 Seconds

Question 1 / 10 Time: 150s

Pluto
In which year was Pluto reclassified as a dwarf planet?
Rule
Why is Pluto not a full planet under the IAU definition?
Discovery
Who discovered Pluto in 1930?
Name
Who suggested the name Pluto?
Ceres
Which dwarf planet is in the asteroid belt?
Eris
Which dwarf planet's discovery in 2005 helped trigger Pluto's reclassification?
Shape
Which dwarf planet is shaped like a stretched egg?
Heart
What did New Horizons find on Pluto in 2015?
Moon
What is Pluto's largest moon?
Count
How many dwarf planets does the IAU currently recognize?

Explanations: answer key for all 10 questions

Q1: In which year was Pluto reclassified as a dwarf planet?
Answer: 2006
The International Astronomical Union voted on a new definition.
Q2: Why is Pluto not a full planet under the IAU definition?
Answer: It has not cleared its orbit of other objects
It shares its region with many Kuiper Belt objects.
Q3: Who discovered Pluto in 1930?
Answer: Clyde Tombaugh
He worked at Lowell Observatory.
Q4: Who suggested the name Pluto?
Answer: An 11-year-old girl, Venetia Burney
She was from Oxford, England.
Q5: Which dwarf planet is in the asteroid belt?
Answer: Ceres
NASA's Dawn orbited it.
Q6: Which dwarf planet's discovery in 2005 helped trigger Pluto's reclassification?
Answer: Eris
It is about as large as Pluto.
Q7: Which dwarf planet is shaped like a stretched egg?
Answer: Haumea
It spins once every four hours.
Q8: What did New Horizons find on Pluto in 2015?
Answer: A heart-shaped plain of ice
It is named Tombaugh Regio.
Q9: What is Pluto's largest moon?
Answer: Charon
It is about half Pluto's size.
Q10: How many dwarf planets does the IAU currently recognize?
Answer: Five
Many more candidates exist.

Dwarf Planets Quiz – Small but Fascinating Worlds

Dwarf planets are round bodies that orbit the Sun but have not cleared their orbital neighborhood of other objects. The IAU created this category in 2006, which moved Pluto from planet to dwarf planet and sparked worldwide debate.

Five dwarf planets are officially recognized: Ceres in the asteroid belt and Pluto, Eris, Haumea and Makemake beyond Neptune. Many more candidates, such as Gonggong, Quaoar and Sedna, may also qualify.

Spacecraft have shown that dwarf planets are surprisingly active. Dawn found bright salt deposits on Ceres, and New Horizons revealed glaciers, mountains and a heart-shaped plain on Pluto. These small worlds hold clues about the early solar system.

What This Quiz Teaches

This quiz is for space fans exploring dwarf planets.

When Pluto was reclassified
Who discovered Pluto
Where Ceres is
What Eris did
What New Horizons found

Did You Know?

Pluto takes 248 years to orbit the Sun.
Ceres was first called a planet in 1801.
Haumea has a ring.
Some of Clyde Tombaugh's ashes flew on New Horizons.
Makemake is named after a Rapa Nui god.