264: What Is a Planet?

Clyde Tombaugh discovered Pluto (indicated by arrows) by detecting its movement in the six days between when these two photos were taken.

Ever since the discovery of the eighth planet, Neptune, astronomers speculated about a possible ninth planet. Some, like American Percival Lowell, used mathematical analysis of the orbit of Uranus to trace the undetected planet’s gravitational effects.

In 1930, astronomer Clyde Tombaugh, building on Lowell’s work, discovered the ninth planet. Or did he? (This is a special Christmas episode of the podcast.)

(Correction: Clyde Tombaugh received his degrees in astronomy from the University of Kansas. In an earlier version of this episode, I mistakenly said they were from Kansas State University. I apologize for the error, and the podcast and transcript have been corrected.)

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Playlist:

Fanfare

Opening Theme

eDream

Closing Theme 



Except when otherwise indicated, the contents of this podcast are © and ℗ 2015, 2016, 2017, 2018, 2019, 2020, 2021 by Mark Painter, all rights reserved. Some music and sound effects used by arrangement with Pond 5.

2 thoughts on “264: What Is a Planet?

  1. Thank you for another great episode! As much as I enjoy the regular flow of the show, it was really interesting to explore a topic from beginning to end – or at least as far as we know today.
    I hope you have a wonderful Christmas with those around you Mark, and I’m looking forward to explore the century further in the coming year.

  2. I too love how the bonus episodes differ from the regular flow. Especially since they’re focussed on ‘space stuff”. Great episode!

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