# Pluto (DD-125)

> Clyde Tombaugh discovered Pluto in 1930 at Lowell Observatory, and it was counted as the ninth planet until August 24, 2006, when the International Astronomical Union defined 'planet' in a way that made Pluto a dwarf planet. NASA's New Horizons flew past in July 2015 and photographed a bright, heart-shaped region named Tombaugh Regio after its discoverer. The heart's western lobe, Sputnik Planitia, is a vast basin of nitrogen, carbon monoxide and methane ices; the eastern lobe is uplands coated with nitrogen ice. The footage shows New Horizons images of Pluto, the observatory dome and icy terrain, with the presenter.

- Department: Space
- First published: 2023-12-16
- Last updated: 2023-12-16
- Permalink: https://detailenjoyer.com/case/pluto/
- Author: Marcus Easterling (DetailEnjoyer), The Detail Department

## On the timeline

- **1930**: Clyde Tombaugh discovers Pluto
- **2006**: The IAU reclassifies Pluto as a dwarf planet
- **July 2015**: New Horizons flies past Pluto

Full timeline: https://detailenjoyer.com/timeline/?case=pluto

## Quick facts

- **DD-125-F01**: Pluto was reclassified as a dwarf planet in 2006. _(Write-up · Exhibit B (Dwarf planet))_
- **DD-125-F02**: Pluto's heart is named Tombaugh Regio. _(Write-up · Exhibit D (Tombaugh Regio))_

## Write-up

Pluto has a heart made of ice. The IAU reclassified Pluto as a dwarf planet on August 24, 2006.

1. **Found in 1930**: Clyde Tombaugh discovered Pluto in 1930.
2. **Dwarf planet**: The IAU reclassified Pluto as a dwarf planet in 2006.
3. **New Horizons**: NASA's New Horizons flew past Pluto in July 2015.
4. **Tombaugh Regio**: Pluto's heart-shaped region is named after Tombaugh.
5. **Sputnik Planitia**: The heart's western lobe is a basin of nitrogen and other ices.

## Related case files

- [Mars Nights (DD-603)](https://detailenjoyer.com/case/mars-nights/): I paired it with another world in our solar system

## Reel vs. record

- **Note**: 'A large plain of nitrogen and other ices': that describes the heart's western lobe, Sputnik Planitia; the eastern lobe is uplands coated with nitrogen ice.

## Video: Pluto: Pluto Has a Heart Made of Ice

- Duration: 23.8 s · Published: 2023-12-16
- File: https://detailenjoyer.com/assets/videos/C067esOOeCZ.mp4

### Transcript

Pluto once considered the ninth planet in our solar system, was reclassified as a dwarf planet by the International Astronomical Union in 2006. DID YOU KNOW? Despite its diminutive size, Pluto has a heart-shaped feature on its surface officially named Tombaugh Regio after Clyde Tombaugh, who discovered Pluto in 1930. This heart-shaped region also known as Pluto's heart or love is a large plain of nitrogen and other ices. NOW YOU KNOW!

## Questions & answers

**Q: Who discovered Pluto?**  
A: In 1930. _(Source: Write-up · Exhibit A (Found in 1930) · NASA Science: Pluto; Wikipedia: Pluto)_

**Q: When was Pluto reclassified?**  
A: By the IAU. _(Source: Write-up · Exhibit B (Dwarf planet) · NASA Science: Pluto; Wikipedia: Pluto)_

**Q: Which spacecraft flew past Pluto?**  
A: In July 2015. _(Source: Write-up · Exhibit C (New Horizons) · NASA Science: Pluto)_

**Q: What is Pluto's heart called?**  
A: It honors its discoverer. _(Source: Write-up · Exhibit D (Tombaugh Regio) · Wikipedia: Tombaugh Regio)_

**Q: What is Sputnik Planitia made of?**  
A: It's the heart's western lobe. _(Source: Write-up · Exhibit E (Sputnik Planitia) · Wikipedia: Tombaugh Regio)_

## Sources

- [NASA Science: Pluto](https://science.nasa.gov/dwarf-planets/pluto/)
- [Wikipedia: Pluto](https://en.wikipedia.org/wiki/Pluto)
- [Wikipedia: Tombaugh Regio](https://en.wikipedia.org/wiki/Tombaugh_Regio)

## Cite this case file

Easterling, Marcus. "Pluto." The Detail Department (DetailEnjoyer), case file DD-125, last updated Dec 16, 2023. https://detailenjoyer.com/case/pluto/