# Second Impact (DD-578)

> Ceres is the largest object in the main asteroid belt between Mars and Jupiter. Giuseppe Piazzi discovered it on January 1, 1801, and it was first hailed as a planet, then called an asteroid. Since August 24, 2006, it has been classed as a dwarf planet, the only one inside Neptune's orbit, though it also keeps its asteroid number, 1 Ceres. NASA's Dawn spacecraft orbited it from March 6, 2015, to the end of the mission on November 1, 2018. Dawn measured a mean diameter of 939.4 km and a mass of about 9.38 × 10^20 kg, about 40% of the whole asteroid belt's mass. It found a crust of ice, salts and hydrated minerals over a muddy interior, with brines that reach the surface in bright spots like those in Occator Crater. Ceres's orbit stays between 2.55 and 2.98 astronomical units from the Sun, well outside Earth's, so the Reel's collision is purely hypothetical. Still, the numbers are extreme. Anything falling to Earth hits at no less than Earth's escape speed, about 11.2 km/s. At 11 to 20 km/s, Ceres would carry about 6 × 10^28 to 2 × 10^29 joules of kinetic energy. That's my own back-of-envelope estimate (½mv²), not a published figure. A 2022 review in Nature Reviews Earth & Environment puts the Chicxulub impact that ended the age of dinosaurs at about 10^23 joules, so Ceres would deliver roughly half a million to two million times as much. Sleep and colleagues estimated in 1989 that an impactor of roughly 350 to 440 km could boil away Earth's oceans, and later models put the threshold nearer 700 km. Ceres is bigger than either. The footage is computer animation of a huge body striking Earth from orbit, with a glowing crater and a fireball sweeping across the planet.

- Department: Space (also Science)
- First published: 2025-05-23
- Last updated: 2025-05-23
- Permalink: https://detailenjoyer.com/case/second-impact/
- Author: Marcus Easterling (DetailEnjoyer), The Detail Department

## On the timeline

- **Jan. 1, 1801**: Giuseppe Piazzi discovers Ceres
- **Aug. 24, 2006**: Ceres is reclassified as a dwarf planet
- **March 6, 2015**: Dawn enters orbit around Ceres
- **Nov. 1, 2018**: The Dawn mission ends

Full timeline: https://detailenjoyer.com/timeline/?case=second-impact

## Quick facts

- **DD-578-F01**: Ceres is about 939 km across and holds about 40% of the asteroid belt's mass. _(Write-up · Exhibit A (The belt's giant))_
- **DD-578-F02**: Ceres has been classified as a dwarf planet since August 24, 2006. _(Write-up · Exhibit B (Planet, asteroid, dwarf planet))_

## Write-up

What if Ceres hit Earth? The 940 km dwarf planet would carry about a million times the dinosaur killer's energy.

1. **The belt's giant**: Ceres is about 939 km across and holds about 40% of the asteroid belt's mass.
2. **Planet, asteroid, dwarf planet**: Found in 1801 and first called a planet, Ceres has been a dwarf planet since 2006.
3. **Dawn's visit**: NASA's Dawn orbited Ceres from 2015 to 2018 and found brines reaching the surface.
4. **A million Chicxulubs**: Hitting at 11 to 20 km/s, Ceres would carry roughly a million times Chicxulub's 10^23 joules.
5. **Oceans boiled**: Studies suggest impactors of about 350 to 700 km could vaporize Earth's oceans. Ceres is bigger.

## Related case files

- [Chicxulub Crater (DD-693)](https://detailenjoyer.com/case/chicxulub-crater/): The dinosaur-killing impact this Reel compares against
- [Nuclear Fireball (DD-052)](https://detailenjoyer.com/case/nuclear-fireball/): Another enormous release of energy in seconds
- [433 Eros (DD-380)](https://detailenjoyer.com/case/433-eros/): I linked more asteroids

## Reel vs. record

- **Note**: 'The largest asteroid in the solar system Ceres': since August 24, 2006, Ceres has been classed as a dwarf planet. It's still the largest object in the asteroid belt and keeps its asteroid number, 1 Ceres, but NASA now calls Vesta the largest asteroid.
- **Note**: 'About 940 km in diameter': correct. Dawn measured a mean diameter of 939.4 km.
- **Note**: 'Energy orders of magnitude greater than the impact that wiped out the dinosaurs': an understatement. By my own back-of-envelope estimate, Ceres hitting at 11 to 20 km/s would carry about 6 × 10^28 to 2 × 10^29 joules. That's roughly a million times the about 10^23 joules estimated for Chicxulub, or about six orders of magnitude.
- **Note**: 'Would vaporize the crust at the impact site': far worse than that. Sleep et al. (1989) estimated that impactors of about 350 to 440 km could boil away the oceans, and later models put the threshold nearer 700 km. Ceres is bigger than either, so an impact would probably sterilize Earth's surface.
- **Missing**: the collision is purely hypothetical. Ceres's orbit stays 2.55 to 2.98 AU from the Sun, far outside Earth's.

## Video: Second Impact: What If Ceres Hit Earth?

- Duration: 26.8 s · Published: 2025-05-23
- File: https://detailenjoyer.com/assets/videos/DKAmnhDSBlO.mp4

### Transcript

DID YOU KNOW? If the largest asteroid in the solar system Ceres, at about 940 km in diameter, were to collide with Earth, the impact would be cataclysmic on a global scale. Ceres, which orbits in the asteroid belt between Mars and Jupiter, contains enough mass to release energy orders of magnitude greater than the impact that wiped out the dinosaurs. A direct collision would vaporize the crust at the impact site, trigger worldwide earthquakes and tsunamis, and inject vast amounts of dust and aerosols into the atmosphere. NOW YOU KNOW!

## Questions & answers

**Q: About how wide is Ceres?**  
A: Dawn measured a mean diameter of 939.4 km. _(Source: Write-up · Exhibit A (The belt's giant) · Wikipedia: Ceres (dwarf planet); NASA Science: Ceres)_

**Q: Since 2006, how is Ceres classified?**  
A: It's the only dwarf planet inside Neptune's orbit. _(Source: Write-up · Exhibit B (Planet, asteroid, dwarf planet) · Wikipedia: Ceres (dwarf planet))_

**Q: Who discovered Ceres in 1801?**  
A: On January 1, 1801, from Palermo. _(Source: Write-up · Exhibit B (Planet, asteroid, dwarf planet) · Wikipedia: Ceres (dwarf planet))_

**Q: Which NASA spacecraft orbited Ceres?**  
A: From 2015 to 2018. _(Source: Write-up · Exhibit C (Dawn's visit) · Wikipedia: Ceres (dwarf planet); NASA Science: Ceres)_

**Q: Roughly how much more energy would a Ceres impact carry than Chicxulub?**  
A: About 10^29 joules against about 10^23. _(Source: Write-up · Exhibit D (A million Chicxulubs) · Wikipedia: Ceres (dwarf planet); Morgan et al., 'The Chicxulub impact and its environmental consequences', Nature Reviews Earth & Environment (2022))_

## Sources

- [Wikipedia: Ceres (dwarf planet)](https://en.wikipedia.org/wiki/Ceres_(dwarf_planet))
- [NASA Science: Ceres](https://science.nasa.gov/dwarf-planets/ceres/)
- [Morgan et al., 'The Chicxulub impact and its environmental consequences', Nature Reviews Earth & Environment (2022)](https://www.nature.com/articles/s43017-022-00283-y)
- [Sleep et al., 'Annihilation of ecosystems by large asteroid impacts on the early Earth', Nature (1989)](https://doi.org/10.1038/342139a0)
- [Citron & Stewart, 'Large Impacts onto the Early Earth: Planetary Sterilization and Iron Delivery', Planetary Science Journal (2022)](https://iopscience.iop.org/article/10.3847/PSJ/ac66e8)

## Cite this case file

Easterling, Marcus. "Second Impact." The Detail Department (DetailEnjoyer), case file DD-578, last updated May 23, 2025. https://detailenjoyer.com/case/second-impact/