New Podcast! Why isn’t Pluto a planet anymore?

If it was good enough for more than 75 years, why not once again?


“The cosmic game changed forever in 1992. Before then, logic told us that there had to be other planets besides the nine (if you still count poor Pluto) in our solar system, but until that year, when two astronomers detected faint, telltale radio signals in the constellation Virgo, we had no hard evidence of their existence.” -Thomas Mallon

In 1930, Clyde Tombaugh discovered Pluto: our Solar System’s ninth planet. For over 60 years, the Plutonian system was the only one known beyond Neptune, and Pluto retained its planetary status for all that time despite its diminutive size. Yet an explosion of exoplanets and of other Trans-Neptunian Objects within our own Solar System beginning in the 1990s meant that we’d need to reconsider what it means to truly be a “planet”. The debate still rages today, but astronomers agree: when it comes to the planetary club, Pluto simply doesn’t belong. Here’s why!


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