Astronomy magazine podcast: Pluto’s demotion

Three experts share their views on the decision to reclassify Pluto with Astronomy Assistant Editor Jeremy McGovern.
By | Published: August 25, 2006 | Last updated on May 18, 2023
When this image was taken, Pluto was 2.6 billion miles from Earth. Pluto has a diameter of 1,440 miles while Charon’s diameter is only 790 miles.
R. Albrecht / ESO / STScI / NASA
The new solar system?
A new definition of “planet” would let Pluto keep its status — and add the asteroid Ceres, Pluto’s largest moon, and 2003 UB313 to the list.
IAU/Martin Kornmesser
August 25, 2006
On August 24, the International Astronomical Union passed in what some consider a controversial vote to redefine the term planet. This resolution reclassified Pluto, long regarded as the 9th planet since its discovery in 1930, as a dwarf planet. In this week’s podcast, planet hunter Mike Brown of Caltech, New Horizons Principal Investigator Alan Stern of Southwest Research Institute, and Patricia Tombaugh, widow of Pluto’s discoverer, share their unique perspectives on the International Astronomical Union’s resolution.
Downloadable File(s)
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Read more about Mike Brown on his web site.

Read more about Alan Stern on his web site. Learn more about New Horizons.