Day 3
How Many Planets in Our Solar System? Glad You Asked!
Saal Granville
Michael Büker
How Astronomy Knew 6 Planets, Then Found 20 More, Then Went Back To 8 (For Now)
The Solar System has had 8 planets ever since Pluto was excluded in 2006. This has made a lot of people very angry and been widely regarded as a bad move. But did you know Neptune was discovered as the 12th planet? Or that, 80 years before Star Trek, astronomers seriously suspected a planet called Vulcan near the Sun? This talk will take you through centuries of struggling with the question: Do you even planet?!

In antiquity, scientists counted the 7 classical planets: the Moon, Mercury, Venus, the Sun, Mars, Jupiter and Saturn – but their model of the universe was wrong. Two thousand years later, a new model was introduced. It was less wrong, and it brought the number of planets down to 6: Mercury, Venus, Earth, Mars, Jupiter, Saturn. Since then, it's been a roller coaster ride of planet discoveries and dismissals.

In this talk, we stagger through the smoke and mirrors of scientific history. We meet old friends like Uranus and Neptune, forgotten lovers like Ceres, Psyche and Eros, fallen celebrities like Pluto, regicidal interlopers like Eris and Makemake as well as mysterious strangers like Vulcan, Planet X and Planet Nine.

Find out how science has been tricked by its own vanity, been hampered by too little (or too much!) imagination, and how human drama can make a soap opera out of a question as simple as: How Many Planets in Our Solar System?