On August 24, 2006, astronomers declared that Pluto is no longer a planet, thereby downsizing the solar system from nine planets to eight. After a week of debate, the International Astronomical Union stripped Pluto of planetary status because its orbit crosses Neptune's and therefore fails one of three planetary requirements. Instead, Pluto (along with Ceres and Xena) is now classified as a dwarf planet.
In conjunction with Newsweek, MSNBC reports on the new view of the solar system. Features include an audio interview with Michael Brown, the Caltech professor who discovered Xena (a nickname for the dwarf planet 2003 UB313), a multimedia solar system map, and related articles (scroll down and look in the right-right column near the bottom of the page.) When you get to the New World Order graphic, be sure to click on Detail to enlarge the map. Do you think Pluto should still be a planet? Vote in the poll to see how others responded.
Although NASA hasn't updated this website to reflect Pluto's demotion, I didn't think any discussion of Pluto would be complete without including the New Horizons spacecraft (launched January 19, 2006) on its way to a 2015 date with Pluto. Mouse around in the Education section to discover printable classroom activities, printable fact sheets, and introductory lessons about Pluto, Charon (Pluto's satellite) and the Kuiper Belt (a "swarm of bodies" beyond Neptune.)
"Discovered by American astronomer Clyde Tombaugh in 1930, Pluto takes 248 years to orbit the Sun. Pluto's most recent close approach to the Sun was in 1989." This NASA site is a must visit for anyone writing a school report. It includes fact and figures, an image gallery, and a Kid's Eye View section with a scale that calculates how much you would weight on Pluto.
This archive of New York Times news articles, editorials, and letters to the editor chronicles Pluto's recent history. The articles marked with the orange "T" logo are for paid subscribers only, but with a simple registration there are plenty of free articles to read. I enjoyed getting a sense of public reaction to Pluto's status change by reading reader's letters and the opinion pieces. For a bit of humor, read Tim Kreider's op-ed "I Heart Pluto."
"Pluto is now officially classified as a dwarf planet. It is one of the largest members of a class of icy spheres known as Kuiper Belt Objects. It has three known moons; one of which, Charon, is very large - almost as big as Pluto itself!" Windows to the Universe is another good site for report research. Clicks worth exploring are the Pluto Image Archive, Planetary Facts, and Pluto's Web (links to external Pluto sites.)