The statistical likelihood that asteroids will destroy us all in 10 million years
Scientists have spent decades discussing whether asteroids and comets hit the Earth at regular intervals.
At the same time, some studies have found that the great extinction events on Earth – like the one that erased the dinosaurs 66 million years ago – are repeated every 26 million to 30 million years.
Since there is good evidence that an asteroid has triggered the extinction of dinosaurs, it makes sense to ask whether asteroid rains could be responsible for regular extinction events.
The question is extremely important – if we can prove that this is the case, we might be able to predict and even prevent asteroids that cause mass extinctions in the future. We tried to find the answer.
Today, there are about 190 impact craters of asteroids and comets on Earth.
They vary in size from only a few meters to more than 100 km across. And they were formed between a few years ago and more than two billion years ago.
Only a few, like the famous meteorite crater in Arizona, are visible to the inexperienced eye, but scientists have learned to recognize impact craters even if they are covered by lakes, the ocean or Thick layers of sediment.
But are these craters formed as a result of regular collisions with asteroids? And if so, why?
There have been many suggestions, but above all, some scientists have suggested that the sun has an accompanying star (called “Nemesis”) in a very wide orbit, approaching the solar system every 26 to 30m d ‘ Years and triggers comet showers.
Nemesis would be a red / brown dwarf star – a weak star type – orbiting the sun at a distance of about 1.5 light years.
This is not an impossible idea, since the majority of stars actually belong to systems with more than one star. However, despite searching for decades, astronomers have not observed it and think they can now exclude its existence.
However, the idea of periodic impacts persists. There are other suggestions.
An idea is based on the observation that the sun moves slightly up and down as it orbits the galaxy, crossing the galactic disk every 30 m or so.
Some have suggested that this could cause comet showers.
But is there evidence that the impacts of asteroids occur at regular intervals? Most research to date has not shown this.
But that does not mean that it is not, it is difficult to get statistics. There are many variables involved: craters disappear as they age, and some are never found in the first place because they are at the bottom of the ocean.
Rocks of certain periods are easier to find than by others. And determining the age of craters is difficult.
A recent study claimed to have found signs of periodicity. However, the crater age data used included many craters with poorly known or even incorrect and obsolete ages.
The methods used to determine age – based on radioactive decay or looking at microscopic fossils with known ages – are continuously improved by scientists.
As a result, today, the age of an impact event can be significantly improved from an initial analysis, say, ten or 20 years ago….