What catastrophic events could lead to life on Earth, as it is known today, coming to an end? Earthlings may not have to lose sleep just yet, but here are four ways that show how life on Earth would come to an end.
1. The Sun Dies
The Sun is approximately 4.5 billion years old with an estimated 5 billion years of hydrogen left – hydrogen is the fuel that drives nuclear fusion on the Sun.
However, once the Sun has converted all its hydrogen into helium it will change from a yellow dwarf into a red giant. In this form its diameter will extend well beyond the orbit of Venus, possibly beyond the orbit of Earth.
When the Sun enters the red giant phase, in which it will spend the final 10% of its lifetime, the Earth will be burned to a cinder.
2. Follow the Dinosaurs
An asteroid or comet could collide with the Earth. Asteroid strikes occur about once every 300 years with varying degrees of destruction.
In 1908, a 60 metre wide asteroid exploded above Tunguska in Siberia, destroying 80 million trees over an area of 2,150 sq km.
If an asteroid or comet hit an inhabited area, the death toll could run into millions. The 1908 collision is referred to as a “small” strike, predicted to happen roughly once every 100 years.
The asteroid that is presumed to have killed off the dinosaurs was more than 10 km in size, and there are craters in Australia and Norway that suggest similar sized impacts have stuck the Earth in the past.
3. Gilese 710 and the Oort Cloud
In approximately 1.4 million years a small star, Gilese 710, travelling toward our solar system at 50,400 km/hr will miss the Earth by roughly 40,000AU (AU – Astronomical Units, a unit of length approximately equal to the distance from the Earth to the Sun).
However, it will crash into the Oort Cloud – the outer layer of the solar system – and send millions of asteroids on a journey through the solar system, possibly on course to collide with the Earth.
In addition, Barnard’s star is expected to come close to the Earth in just 10,000 years.
4. Hypernova
An enormous dying star at least 40 times the size of our Sun, collapsing into a black hole within 3,000 light years of Earth, would be enough to kill all life instantly, including bacteria.
It would swamp the planet with intense radiation of up to 1 million times the strength of an x-ray.
The nearest massive star is 7,500 light years away, still close enough to do some potential damage to satellites in the southern hemisphere, but not near enough for radiation to penetrate down to the surface.
The solar system has already survived some hypernovae and no more stars remain a threat.
