In this part of the lesson, students get to learn more about the history of the discovery of Pluto and the redefinition of it from a planet to a dwarf planet, or plutoid. They should use the resources on the Is Pluto a Planet? student esheet to answer the questions on the student sheet. Here are the answers to the questions.
When was Pluto discovered? Who made the discovery?
Pluto was discovered on February 18, 1930, by Clyde Tombaugh, an observing assistant working at the Lowell Observatory.
What are some characteristics of Pluto?
Pluto is a frigid world, billions of kilometres from Earth, and 30 times less massive than the then-smallest known planet, Mercury. It has three satellites.
What happened on August 20, 1992, and how did it change our view of the solar system?
David Jewitt and Jane Luu discovered the first of 1000 now known objects orbiting beyond Neptune in what is often referred to as the transneptunian region.
What did Mike Brown, Chad Trujillo, and David Rabinowitz discover on October 21, 2003? What is its significance?
They discovered a Transneptunian Object (TNO) with a satellite orbiting the sun that was more massive than Pluto.
What happened in August 2006?
The International Astronomical Union voted to redefine Pluto as a dwarf planet.
According to Michael Brown, how did this decision affect our perception of the solar system?
He claims that saying Pluto isn’t a planet anymore takes something out of our picture of what the solar system should be.
Why do you think Dr. Brown says that our picture of the solar system was a “cartoon picture”?
Answers may vary. Encourage students to explain their responses.
Where is the Kuiper Belt located?
It is at the far reaches of the solar system, where Pluto orbits.
What three dwarf planets did Dr. Brown and his team discover?
They discovered Eris, Makemake, and Haumea.
According to Dr. Brown, what is the mission of a scientist?
It is to be the first to make a discovery and also to be first to provide explanations of a discovery.
What are some of the problems encountered by scientists involved in this kind of research?
Scientists can find that after all of their research and their work on a paper that explains their research, someone else who is doing the same kind of research publishes or announces the discovery first.
What was Dr. Brown’s reaction to the demotion of Pluto and the “tenth” planet that he had found?
He was thrilled because it meant that the word planet had scientific meaning.
What is Dr. Brown’s hope for our view of the solar system?
He hopes that we can move from a cartoon view of the solar system to a real picture of the solar system—we go to a deeper scientific understanding of the solar system.