Could asteroids bombard the Earth to cause a mass extinction in 10m years?
Scientists have spent decades discussing whether asteroids and comets hit Earth at regular intervals. At the same time, some studies have found signs that major extinction events on Earth – such as the one that wiped out dinosaurs that are 66 million years old – are repeated every 26 to 30 million years.
Since there is good evidence that an asteroid caused the extinction of dinosaurs, it is logical to wonder if the asteroid rain could be responsible for the regular extinction events.
The issue is extremely important – if we can prove that this is the case, we may be able to predict and even prevent asteroids that cause massive extinctions in the future. We have tried to find the answer.
Today, there are about 190 impact craters of asteroids and comets on Earth. Its size varies from a few meters to more than 100 km in diameter.
And they are formed between the last years and there are more than two billion years. Only a few, such as the famous “meteor crater” in Arizona, are visible to the untrained eye, but scientists have learned to recognize the same impact craters are covered by lakes, or at sea thick layers of sediment.
But did these craters form as a result of regular asteroid collisions? And if so, why? There were many suggestions, but above all, some scientists have suggested that the sun has a companion star (called “Nemesis”) in a large orbit, approaching the solar system every 26 to 30 million years, which caused a rain Of comets.
Nemesis is a red / brown dwarf – a small type of star – that orbits the sun at a distance of about 1.5 light years.
This is not an impossible idea, since most stars actually belong to systems with more than one star. However, despite the search for decades, astronomers have not seen and believe they can now exclude their existence.
However, the idea of periodic impacts persists. There are other suggestions. One idea is based on the observation that the sun moves slightly up and down as it orbits the galaxy through the galactic disk every 30 m. Some have suggested that this can lead to a shower of comets.
But is there evidence that asteroid impacts occur at regular intervals? Most research to date has not been shown to.
But that does not mean that this is not the case, it is difficult to get statistics. There are many variables involved: craters disappear as they age, and some are never found, first, as they are at the bottom of the ocean.
Rocks of certain periods are easier to find than others. And determining the age of the craters is difficult.
A recent study claimed to have recurring signs of recurrence. However, the crater age data used included many craters with little known or even erroneous and obsolete ages.
The methods used to determine age – based on radioactive decay or see microscopic fossils with known ages – are constantly being improved by scientists.
So, today, the age of an impact event can be significantly improved from an initial analysis, for example, there are ten or 20 years.
Another problem is related to the impact that identical identical ages have with exactly the same uncertainty in the era known as the “age grouped.” The age of an impact crater may be, for example, 65.5 ± 0.5 m years, while the other is 66.1 ± 0.5 m years.
In this case, the two craters could be the same age of 65.8 m real years. Such craters in some cases have been produced by impacts of asteroids accompanied by small moons or asteroids that burst in the atmosphere.