How Big Was the Asteroid That Contributed to Dinosaur Extinction?
The asteroid that struck Earth 66 million years ago and accelerated the extinction of dinosaurs was about 10 to 15 km (6 to 9 miles) in diameter.
www.britannica.comDirect answer: Most scientists estimate the asteroid that contributed to the dinosaur extinction was about 10–15 kilometers (6–9 miles) in diameter, creating the Chicxulub crater about 180 kilometers (112 miles) wide. This view is widely cited in recent summaries and Britannica’s 2026 update, reflecting a consensus built on crater size and global effects evidence.
Latest context and quick notes:
- The Chicxulub impact is the leading explanation for the K–Pg extinction, with crater size supporting a multi-megaton energy release and global environmental collapse.
- Some sources reiterate the 10–15 km diameter range and a ~180 km crater, aligning with modern reviews and updated Britannica material.
- Ongoing research continues to refine the asteroid’s origin and composition, but size estimates have remained stable around the 10–15 km range.
Illustration: A compact visualization you might find helpful is a comparison of asteroid diameters:
- 10 km asteroid vs. Chicxulub crater ~180 km across; the crater is roughly 18 times larger in diameter than the asteroid, illustrating how a relatively small body can unleash a planet-wide effect.
If you’d like, I can pull the most current primary sources or summarize a few specific recent articles.