Why Isn't Pluto a Planet Anymore?

Which of the following planets were identified by ancient Babylonian astronomers?

• Uranus, Neptune, and Pluto

• Mercury, Venus, and Earth

• Mercury, Venus, Mars, Jupiter, and Saturn

• Earth, Mars, and Jupiter

From which ancient language does the word "planet" originate, and what does it mean?

• Latin, meaning "shining star"

• Greek, meaning "wanderer"

• Egyptian, meaning "celestial body"

• Sanskrit, meaning "traveler"

Who was the first person to officially discover Uranus?

• Galileo Galilei

• Johann Galle

• Sir William Herschel

• Clyde Tombaugh

What is the third criterion an object must meet to be classified as a planet, which Pluto failed?

• It must orbit the Sun.

• It must be large enough to be a sphere due to its own gravity.

• It must have at least one moon.

• It must clear the neighborhood of its orbit.