Canopus Nuclear Test
France · 1968 · 2.6 megatons · thermonuclear (hydrogen bomb)
Overview
First French H-bomb test.
With a yield of 2.6 megatons[1], the Canopus is 173× more powerful than the Hiroshima bomb. As a thermonuclear (hydrogen bomb) weapon, it derives its energy from a fission explosion that ignites fusion fuel, releasing on average roughly equal energy from fission and fusion. [2]
Canopus Blast Effects
The table below shows the calculated radius of each effect zone for an air burst at optimum height. Values are scaling laws from The Effects of Nuclear Weapons (Glasstone & Dolan, 1977) and the published effects scaling table[3, 4].
| Effect zone | Radius (air burst) |
|---|---|
| Fireball radius | 1.42 km |
| Severe blast (20 psi) | 3.28 km |
| Moderate blast (5 psi) | 8.55 km |
| Light blast (1 psi) | 23.5 km |
| 3rd-degree thermal burns | 17.3 km |
| 2nd-degree thermal burns | 21.1 km |
| 1st-degree thermal burns | 26.4 km |
All radii assume an air burst at optimum height and are 1-D ground-distance estimates from the detonation point. Real-world effects depend on terrain, weather, and building construction. Casualty and fallout estimates are not shown pending a verified population and fallout model.
Run the Canopus on a City
Use the interactive simulator to detonate the Canopus on any city worldwide. Click any location on the map to see the fireball, blast, and thermal radii (air burst at optimum height) overlaid on real geography.
🎯 Simulate CanopusRelated Weapons
FAQ
How big is the Canopus blast radius?
In an air burst at optimum height, the Canopus produces a fireball roughly 1.42 km in radius and a 5 psi moderate-blast zone of about 8.55 km — the area in which most residential buildings would collapse. The 1 psi light-damage radius extends to roughly 23.5 km, where windows shatter.
What is the yield of the Canopus?
The Canopus has a yield of 2.6 megatons of TNT equivalent. That is 173× more powerful than the Hiroshima bomb.
Is the Canopus bigger than the Hiroshima bomb?
The Hiroshima bomb (Little Boy) had a yield of approximately 15 kilotons. The Canopus at 2.6 megatons is 173× more powerful than the Hiroshima bomb.[5]
What thermal burn radius does the Canopus produce?
In an air burst at optimum height, thermal radiation from the Canopus can cause 3rd-degree burns out to roughly 17.3 km, 2nd-degree burns to 21.1 km, and 1st-degree burns to 26.4 km.
Sources
- 1.Source: Wikipedia, List of nuclear weapons tests — retrieved Oct 2026
- 2.Source: US DoD & ERDA (Glasstone & Dolan), via Atomic Archive, The Effects of Nuclear Weapons, 3rd ed. (1977), Chapter 1 — retrieved Oct 2026
- 3.Source: U.S. DoD / DOE (Glasstone & Dolan, via Atomic Archive), The Effects of Nuclear Weapons, 3rd ed. (1977) §2.127 — retrieved Oct 2026
- 4.Source: Wikipedia, Effects of nuclear explosions — scaling-law table — retrieved Oct 2026
- 5.Source: US DOE / NNSA Nevada Field Office, United States Nuclear Tests, July 1945 through September 1992 (DOE/NV-209 Rev. 16, Sep 2015), NNSS publication library — retrieved Oct 2026