In 2006 Pluto was famously “demoted” from planet to dwarf planet, and plenty of people are still cross about it — but the real story is far more interesting than a snub. This episode explains what actually happened, and the vast frozen frontier of the solar system that Pluto belongs to.

You’ll come away understanding why astronomers changed Pluto’s status, what the word “planet” really means, what the Kuiper Belt is, and what the New Horizons spacecraft revealed when it finally reached this distant little world.

Talking Science is sponsored by Kinsoft. Visit www.kinsoft.com.au

Further reading: NASA – “New Horizons” mission pages; International Astronomical Union – “Pluto and the Developing Landscape of Our Solar System”; Mike Brown, How I Killed Plut ...