Comet is the origin of the ocean?

Scientists have long suspected that the Earth and its neighbor were " attacked" by tens of thousands of objects in an ancient event known as Late Heavy Bombardment.

This "attack" phase distorted the moon, leaving a large impact hole still visible, preserved over millennia in the moon's airless environment. However, it is unclear whether these colliding objects are ice comets or rock meteorites.

Based on the amount of metal in the ancient Earth's rock, a research team led by Uffe Jorgensen of the Niels Bohr Institute in Denmark says comets are the "culprits".
Jorgensen said the topic of whether the earth's oceans existed before the comet 'visited' was debated.

Some experts argue that a sufficient amount of water to form the ocean existed right from the early days of the Earth, while others argued that the Earth's heat when young had vaporized any substance. liquid

'This is one of the topics that can make scientists jump into each other', Jorgensen commented.

His team thinks that the early Earth was too hot to hold a large amount of water. But by the time of the Late Heavy Bombardment event, everything that had cooled down allowed water to dissolve from the comet of comets to become the first ocean in the world.

'We have swallowed a part of the impact object every time we drink a glass of water', the authors of the study wrote in the paper will be published in the next issue of Icarus magazine.

Metal of comets

Jorgensen and colleagues concluded this after measuring iridium concentrations in surface rocks and near the surface from Greenland - one of the oldest rocks in the world.

Iridium is a rare metal on Earth, but popular in comets and meteors.

According to the team's calculations, the concentration of iridium in the rocks around a meteorite impact pit is about 18,000 parts per million.

Meanwhile, comet collisions only leave about 130 parts per million, because comets contain less metal, because they are composed primarily of ice blocks and some rock debris.

Comet is the origin of the ocean? (Photo: nationalgeographic.com)

Comets also crashed into Earth at a greater speed because their orbits turned around their longer sun.

Therefore, 'the explosion formed by a comet is often more intense than a meteorite collision, and the amount of matter - including iridium - is pushed back into space is also greater,' explains Jorgensen.

The team found that the stone in Greenland contains about 150 parts per million of iridium, reinforcing the idea that the comet itself is the objects that hit the Earth in the Late Heavy Bombardment event.

All ice from the comet gathers and dissolves to form the first ocean at a depth of half a mile (about 1 km), according to the team's calculations.

Meanwhile the moon has no ocean because its gravity is much weaker than the Earth, so most, if not all, fragments from comets hit the moon are pushed back into space.

However, Nicolas Dauphas, a geophysicist at the University of Chicago, is still not completely convinced that objects colliding with Earth are comets, not meteorites.

The new study, he said, depends too much on estimation - for example, the predicted amount of iridium settles after a collision.

Dauphas said: 'I am concerned that they have extended their conclusions too far.'

Accidental life?

Chandra Wickramasinghe, an extraterrestrial biologist at Cardiff University, UK, who is not involved in the study, also supports the theory of a mass comet collision.

And he thinks that comets may not only bring water but also life to Earth.

According to some controversial studies, the oldest evidence of life on Earth comes from 3.85 billion years ago, coinciding with the time of the Late Heavy Bombardment.

Wickramasinghe said: 'It may be a coincidence, but for me it is a coincidence too much.'

The co-author of the study Jorgensen fully agrees.

He said: 'This event is an accident, an accident. But if it doesn't happen, there will be no water and life on Earth. '