Pluto at 90: how Clyde Tombaugh discovered a new world

This episode we mark the 90th anniversary of Pluto's discovery by exploring the life of US astronomer Clyde Tombaugh, and take a look at the Pluto's rise and fall as the 9th Solar System planet. Plus, we examine a recent International Astronomical Union campaign that saw 112 countries around the world name newly-discovered exoplanets.

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