Test: English Language Proficiency Test

Since its discovery and classification as the ninth planet in our solar system in 1930, Pluto has been the subject of much controversy in the scientific community.  Its small size and extreme distance from Earth have made gathering specific data about its characteristics difficult, and no real consensus exists amongst astronomers about the information that is known about Pluto.  In 2006, the International Astronomical Union created an official definition for the term "planet" which listed three criteria for classification:

  1. The object must be in orbit around the sun.
  2. The object must be massive enough to be rounded into a sphere by its own gravity.
  3. The object must have "cleared the neighborhood" around its orbit.

Because Pluto is much smaller than the other objects in its orbit, it fails to meet the third condition and has since been known as a "dwarf planet".  Some scientists have gone so far as to suggest that Pluto may actually be one of the many moons of its neighboring planet, Neptune.

When Pluto was first discovered in 1930, astronomers estimated that it may be as large as earth and thus were confident that it was, in fact, a planet.  As our ability to gather information about outer space continues to improve through more powerful telescopes and space probes, scientists are now able to use the new, more accurate information they receive to accurately classify objects in space.  While some still argue that Pluto meets the accepted criteria to be known as a planet, for the time being, conventional scientific thinking will hold that our solar system only has eight planets.


The writer provides the criteria established by the International Astronomical Union in order to _____________________.

provide a criteria that supports the argument that Pluto is not large enough to be classified as a planet

show the mistakes made by astronomers who classified Pluto as a planet in 1930

explain the differences between planets and "dwarf planets"

prove that scientists now have enough data to accurately classify all objects in our solar system

1/3 questions


Access results and powerful study features!

Take 15 seconds to create an account.
Start now! Create your free account and get access to features like:
  • Full length diagnostic tests
  • Invite your friends
  • Access hundreds of practice tests
  • Monitor your progress over time
  • Manage your tests and results
  • Monitor the progress of your class & students
By clicking Create Account you agree that you are at least 13 years old and you agree to the Varsity Tutors LLC Terms of Use and Privacy Policy.
Learning Tools by Varsity Tutors