# The Search for Planet X

- Institution: Gresham College
- Speaker: Professor Ian Morison
- Year: 2009
- Level: For everyone
- Language: English
- Subjects: Astronomy and space
- Source: [Gresham College](https://www.gresham.ac.uk/watch-now/search-planet-x)
- Licence: [Educational use (Gresham College's terms)](https://www.gresham.ac.uk/terms-and-conditions)
- Who can watch: Tweens profiles and older (sources give no ratings; placed by Invisible Network from the source's own words)

The lecture will describe the nearly 200-year-long detective story of the search for planets in the outer reaches of the Solar System. It led first to the discovery of Neptune and Pluto and, recently, to Pluto's downgrading to a 'Dwarf Planet'. We already know of a second dwarf planet beyond Pluto; what others might there be?

## Lectures

1. [The Search for Planet X](https://invisiblenetwork.ai/learn/gresham/search-planet-x/574903aef22a) (YouTube)