The meteor that killed the dinosaurs is estimated to have been about 10–15 km (6–9 miles) wide.

How big was it, really?

Most modern studies focus on the Chicxulub impactor, the asteroid that hit what is now the Yucatán Peninsula in Mexico about 66 million years ago.

  • Many geologists estimate its diameter at roughly 10–15 km.
  • Some descriptions round this to about 6+ miles (≈10 km) across when explaining its effects, like the global tsunami it triggered.

For a feel of scale: that is a rock roughly the size of a major city slamming into Earth at tens of thousands of kilometers per hour.

What kind of crater did it make?

The impact carved out the Chicxulub crater, now buried under the Yucatán.

  • The crater is about 150–180 km (≈110 miles) wide and up to 20 km (12 miles) deep , though later sediments have partly filled it.
  • That crater size fits with impact models for a 10–15 km wide asteroid hitting at high speed.

What did that mean for Earth?

When that 10–15 km asteroid struck:

  • It released energy far beyond any human-made explosion and even the largest earthquakes, with some work estimating the impact energy as tens of thousands of times that of major modern quakes.
  • It triggered mega-tsunamis with waves up to kilometers high near the impact site and enormous global tsunamis across the oceans.
  • The event is widely accepted as the main trigger of the mass extinction that wiped out non-avian dinosaurs and about three-quarters of species on Earth.

TL;DR: The meteor that killed the dinosaurs was roughly 10–15 km (6–9 miles) across , big enough to dig a crater about 180 km wide and to reset life on Earth.