August 24, 2006 - The International Astronomical Union has stripped Pluto of its planetary status. Pluto was discovered in 1930 by American astronomer Clyde Tombaugh of Arizona's Lowell Observatory and classified as a planet. In 2003, Pluto’s standing was called into question when astronomers found a larger object, UB313, in the Kuiper Belt, an area beyond Neptune filled with large icy objects and believed to be the source of many comets.

Approximately 2,500 experts at the IAU’s general assembly voted to change Pluto’s status, rejecting a proposal that would have retained Pluto as a planet and brought three other objects into the planetary club. Pluto is considerably smaller and more distant than the other planets in our solar system. Two-thirds the size of Earth's moon, Pluto's classification as a planet came under scrutiny when many objects of similar size and distance were discovered in the Kuiper Belt in the 1990s.

The Space Studies Board provides an independent, authoritative forum for all aspects of space science and applications, and it serves as the focal point within the National Academies for activities on space research.

The Board on International Scientific Organizations examines issues related to the international conduct of science; evaluates opportunities for international collaboration in scientific research; and strengthens U.S. participation in international scientific organizations such as the IAU.

• Space Studies Board
• Board on International Scientific Organizations

• NASA's Pluto Profile