Question Corner | Was the evolution of the Earth’s atmosphere affected by asteroid, comet strikes?

Now, a study by U.S. researchers analysed remnants of ancient asteroids and modelled the effects of their collisions to show that the strikes took place more often than previously thought.

Between 2.5 and 4 billion years ago it was not uncommon for asteroids or comets to hit the Earth. In fact, the largest ones, more than 9 kilometres wide, altered the chemistry of the planet’s earliest atmosphere.

Now, a study by U.S. researchers analysed remnants of ancient asteroids and modelled the effects of their collisions to show that the strikes took place more often than previously thought. These strikes may have delayed when oxygen started accumulating on Earth, says a Harvard University press release. The new models can help scientists understand more precisely when the planet started its path toward becoming the Earth we know today.

The researchers found existing planetary bombardment models underestimate how frequently asteroids and comets would hit Earth. The new, higher collision rate suggest impactors hit the planet roughly every 15 million years, about 10 times higher than current models.