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Pluto a Planet No More



Subject(s) Science --Space Science


Grades 2-up

News Content

Scientists' new definition of a planet means Pluto is being demoted. Now we have only eight planets instead of nine.

Anticipation Guide

Before reading, ask students to help you create a list of planets in the solar system. Are your students able to list all nine of the planets? (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto)

You might even see if your students can name all nine planets in order of their distance from the sun. If some students know the planet names in order, ask how they know them. Do they have a trick for remembering the planets' sequence?

Next, provide students with a copy of this week's News for You news article, Pluto a Planet No More. (You could print copies for students or you could project a copy of the news story on a screen.) Some students might be aware already of the latest news -- that astronomers have removed Pluto from the list of planets.

News Words

Write the following news words on a board or chart: astronomers, orbit, planet, solar system, distance. Then read aloud each statement below. Ask students to use one of the News Words to complete each statement:

  • All of the planets in our ____ orbit around the sun. (solar system)
  • The planet Neptune is a long ____ away from Earth. (distance)
  • Earth travels in a circular ____ around the sun. (orbit)
  • Scientists who study the planets and stars are called ____. (astronomers)

Read the News

Click for a printable version of this week's news story Pluto a Planet No More.

Reading the News

You might use a variety of approaches to reading the news:

* Read aloud the news story to students as they follow along.

* Students might first read the news story to themselves; then call on individual students to read the news aloud for the class.

* Arrange students into small groups. Each student in the group will read a paragraph of the story. As that student reads, others might underline important information or write a note in the margin of the story. After each student finishes reading, others in the group might say something -- a comment, a question, a clarification -- about the text.

More Facts to Share

  • You might share these additional facts with students after they have read this week's news story.
  • The decision to remove Pluto from the list of planets was not an easy one to make; it came at the end of a week of disagreements at a meeting of the International Astronomical Union. More than 2,500 astronomers from 75 countries were at the meeting.
  • The decision established three categories for objects in space: planets, dwarf planets (or minor planets), and small solar system bodies (such as asteroids and comets).
  • Pluto was discovered by Clyde Tombaugh in 1930. Tombaugh died in 1997, and some of his ashes are aboard the New Horizons spacecraft, which NASA launched earlier this year on a 9-1/2-year journey to Pluto. The spacecraft is expected to pass near Pluto around July 14, 2015.
  • The new definition of a planet calls for it to "clear the neighborhood around its orbit." But the orbit of Pluto is not all its own. The orbits of Neptune and Pluto cross paths. There are actually times when Pluto is inside of Neptune's orbit and Neptune is farther from the sun than Pluto is.
  • In 2003, Michael Brown of the California Institute of Technology discovered an icy object larger than Pluto that was once thought to be a new planet. Now that object, called UB313 (or Xena), will join Pluto as a dwarf planet. UB313 is the largest dwarf planet.
  • Some science teachers found the news of Pluto's demotion exciting. "It's a chance to teach kids that this is the nature of science. Things are always changing," Arizona teacher Rich Hogen told CNN.

Comprehension Check
Recalling Detail

  • How many of the nine planets can you name now that we have read the news story? (Are students able to name all of the planets?)
  • For how long has Pluto been called a planet? (76 years)
  • What are the rules that will help scientists determine in the future if a space object is a planet or not? (A planet must orbit the sun; be large enough to have almost a round shape; and have its own clear orbit.)
  • Which planet is closest to Pluto? (Neptune)
  • What new name have scientists given to space objects similar to Pluto? (dwarf planets)
  • Who discovered Pluto? (Clyde Tombaugh)

Follow-Up Activities

Critical Thinking. Challenge your students to come up with a new mnemonic to help them learn the names of the eight planets in their correct sequence from the sun. In a news article on, the following sentences were suggested as possibilities:

  • My Very Extravagant Mother Just Sent Us Nachos.
  • My Very Elderly Mother Just Sits Up Nights.
  • Major Volcanoes Erupt, Making Jolts, Shaking, Unsteadying Nerves.
  • Make Very Extraordinary Meals of Jell-O, Strawberries and Unsalted Nuts.
  • Mary's Violet Eyes Make Jack Stare Until Noticed. Maybe your students can come up with an even better mnemonic.
Note: They might even be able to come up with a mnemonic that provides an easy way to remember which of the M planets -- Mercury or Mars -- is closest to the sun. For example the old mnemonic

Men Very Early Made Jars Serve Useful Needed Purposes

helps students remember that Mercury is closer to the sun because the word Men begins with the two letters M-e, which are also the first two letters of Mercury. The words Made begins with M-a, which are the first two letters of Mars.

Music. The song The Family of the Sun, created by Melvin Zisfein and Robert W. Wolfe of the Smithsonian's National Air and Space Museum, is a fun tune for teaching students about the planets. Of course, the song will need some minor rewrites now.


Use the Comprehension Check (above) as an assessment. Or have students work on their own (in their journals) or in their small groups to respond to the Think About the News questions on the printable news story page.

Lesson Plan Source

Education World

National Standards

National Standards

NL-ENG.K-12.2 Reading for Understanding
NL-ENG.K-12.12 Applying Language Skills

NS.K-4.4 Earth and Space Science
NS.K-4.7 History and Nature of Science
GRADES 5 - 8
NS.5-8.4 Earth and Space Science
NS.5-8.7 History and Nature of Science
GRADES 9 - 12
NS.9-12.4 Earth and Space Science
NS.9-12.7 History and Nature of Science

See recent news stories in Education World's News Story of the Week Archive.

Article by Gary Hopkins
Education World®
Copyright © 2006 Education World