For thousands of years, Martian rocks have been flying through space, colliding with Earth and being ejected from their homeland by violent impacts and volcanic activity. But as they collected these small samples, scientists began to learn something interesting. That means the age of these Martian rocks doesn’t match what we know about the age of Mars as a whole. They are much younger.
Mars is really old. Scientists believe this planet finished forming about 4.56 billion years ago, about 90 million years before our planet. Additionally, there is evidence that much of Mars’ surface is ancient. So why do Martian rock blocks indicate such a young age?
The answer, they say, likely lies in the constant bombardment of Mars’ surface by meteorites and asteroids. About 200 bombardments occur every year, creating a 4-meter crater, and the Martian surface is constantly spewing more rocks into space, some of which reach Earth. The reason why Martian rocks don’t seem to be the right age is because younger rocks replace older rocks as they are ejected from the planet.
This means that young rocks below the Earth’s surface, which are still being replenished by volcanic activity, will eventually be exposed to the surface and become the ejecta that meteorites send into space. This is explained in a paper published in 2016 by a group of scientists. Earth and Planetary Science Letters, This may help us understand why Martian rocks found on Earth appear so young.
As NASA and others prepare for the first human mission to Mars, understanding how Mars is changing both internally and externally is important. Additionally, scientists are constantly looking for new ways to understand how the planets in our solar system formed, and thereby learn more about the evolution of the universe as a whole.