The late heavy bombardment: an important source of life on the Earth?

An artists impression of our moon during
and after the late heavy bombardment

You might wonder how comes there are so many craters on the planets and moons. Scientists say that this is due to the late heavy bombardment which is an hypothetical event that happened around 3.8 to 4.1 billion years ago. During this event a large number of comets and meteoroids would have collided with Earth and all the other planets and moon.

The late heavy bombardment had also affected our planet Earth. There had been 22,000 or more craters with diameters less than 20 km and about 40 craters with diameters that are about 1000 km and several craters that are about 5000 km in diameter on Earth. These collisions could have been the source of life on Earth because some of these comets that collided with Earth were made of ice and then the ice melted to form water which paved the way for life.


An artists impression of Eta Corvi and
a planet being hit by a shower of comets

Such event not only happened in our solar system. Evidence shows that another star from the constellation Corvus also had an event that is similar to our own late heavy bombardment. That star is called Eta Corvi. It is a F-type main sequence star which is similar to the sun in our own solar system. Eta Corvi is a white star that is in its main stage of life. It is 40% larger than the sun but 30% younger than the sun.



A meteorite

There are many theories on how this event had happened, but to me the most probable reason is the hypothesis put forwarded by Professor Brian Cox in my favourite BBC documentary "Wonders of the Solar System". He suggested that Jupiter and Saturn would meet up once every two years due to their different orbits. When they met up around 3 to 4 billion years ago, their combined gravity had pushed Neptune into the directions of some comets and meteorites. Neptune would have then knocked the comets and meteorites out of their usual orbits. These comets and meteorites disturbed by Neptune then hit all the planets and moons.

Conclusion: This solar system would have been very different and less interesting if this event had not happened. Also we might not be here if this event did not happen. For these reasons I give this event on the level of importance a 9/10.

Photo Credits:
An artists impression of our moon during and after the late heavy bombardment: By Timwether (Own work) [CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0) or GFDL (http://www.gnu.org/copyleft/fdl.html)], via Wikimedia Commons http://commons.wikimedia.org/wiki/File%3ALunar_cataclysm.jpg:

An artists impression of Eta Corvi and a planet being hit by a shower of comets: By NASA/JPL-Caltech [Public domain], via Wikimedia Commons
http://commons.wikimedia.org/wiki/File%3AIt's_Raining_Comets_(Eta_Corvi).jpg

A meteorite: By NASA [Public domain], attraverso Wikimedia Commons
https://commons.wikimedia.org/wiki/File%3AGalileo_Gaspra_Mosaic.jpg