Planet Classification and Characteristics

The video discusses Pluto's discovery in 1930 and its initial classification as the ninth planet. Over seventy-five years later, Pluto was reclassified as a dwarf planet due to new discoveries in the Kuiper Belt, including Eris, which challenged its planetary status. The International Astronomical Union (IAU) established criteria for defining a planet, which Pluto did not fully meet. The term 'dwarf planet' was introduced for celestial bodies like Pluto that orbit the Sun and are nearly round but have not cleared their orbits. Currently, five objects are classified as dwarf planets: Pluto, Eris, Ceres, Haumea, and Makemake.

What year was Pluto discovered and initially classified as the ninth planet?

• 1920

• 1940

• 1950

• 1930

What region beyond Neptune's orbit was discovered in 1992, leading to debates about Pluto's classification?

• Scattered Disc

• Kuiper Belt

• Oort Cloud

• Asteroid Belt

Which object discovered in 2005 was thought to be larger than Pluto?

• Makemake

• Eris

• Ceres

• Haumea

What year did the International Astronomical Union form a committee to define the characteristics of a planet?

• 2009

• 2000

• 2003

• 2006

Which of the following is NOT a criterion for an object to be classified as a planet according to the IAU?

• Has enough mass to be round

• Orbits around the Sun

• Has cleared its orbit of other objects

• Is the largest object in its orbit

How many objects are currently classified as dwarf planets in the solar system?

• Three

• Nine

• Five

• Seven

Which of the following is NOT classified as a dwarf planet?

• Pluto

• Eris

• Europa

• Ceres