Summary

Water is the most valuable and important source to be found on our planet. But how did Earth obtain its water supply, while other planets remain devoid if it? In this video, Zachary Metz gives a brief explanation to multiple contending theories of the ancient origins of Earth’s water.

Why watch this video? 

• Have you ever wondered where our water supply came from?
• Would you like to know why it is that Earth has the most abundant water supply in the solar system?
• Have you ever been confused by how water came to exist on Earth?

Key terms

Nucleosynthesis: the process in which existing atoms fuse to form heavier elements, anything more complex than the basic hydrogen.

Outgassing: the process which ultimately resulted in the formation of Earth’s first atmosphere, in which volcanic gas released from molten rock within the Earth’s core would result in a layer above the Earth.

Loose ends

What is a supernova? How is it different from a star?

Contrary to popular belief, the supernova is not an existing entity (e.g. a super big star), rather it is an event – the death of a star, in which in its final stage of life, and not to be technically considered a star. In this event, we can witness it go out in a blinding burst of light. According to NASA, supernovas are the “largest explosion that takes place in space”.

Why is it so hard to find water anywhere else in the solar system?

One of the unique characteristics of Earth is its abundance of liquid water. There are many theories as to why Earth is the only planet with liquid water. Some scientists say it’s the Earth’s location in the solar system, in which our distance from the sun is just perfect enough to make it possible – in which we are not too close (because then we would receive too much heat/energy) but not too far (otherwise we’d freeze). Additionally, scientists say there is a relationship between Earth’s plate tectonics and the production of water. As said by Diane Valencia from Harvard University, “the fact that Earth has plate tectonics allows for the carbon-silicate cycle to operate over the geological timescale. With the carbon-silicate cycle, the levels of carbon in the atmosphere get regulated to keep the surface temperature around that of liquid water.” There is no definitive answer as to if the water on Earth today is the same as the water that first formed, or not at all.

What is the difference between an asteroid and a comet? What is a meteor?

Comets are composed of ice, rock and dust and typically orbits the sun. Its debris often results in what is known as a meteoroid, which is often composed of rock or metal and is much smaller in size. It also orbits the sun. When a meteoroid enters the Earth’s atmosphere and burns up; in this context, the meteoroid is then known as a “meteor”. Most meteoroids never manage to reach earth as a result, as they typically vaporize immediately upon reaching the Earth’s atmosphere. An asteroid, on the other hand, is arguably the largest in size of all these – traditionally anything measuring larger than 10 meters across is to be categorized as an asteroid. However, they do range in size – the largest asteroid recorded in size being Ceres which was 952km in diameter (592 miles); large enough to possibly be considered a dwarf planet. Asteroids also orbit around the sun and are composed of metal and rock.

Self-Test Questions