Where did Earth’s water come from? - Zachary Metz

Summary

Water, a vital part of Earth, has a cosmic origin. It makes up 60% of our bodies and 70% of the Earth's surface, but is rare in the rest of the solar system. Formed from hydrogen and oxygen created in stars, water molecules were present during the formation of our planet. The mystery lies in how and when water arrived on Earth—either during its formation or through asteroid impacts. This cosmic journey shows that the water we rely on today came from deep space, potentially much earlier than we previously thought.

Takeaways

• 💧 Water is tasteless, colorless, and odorless, making it easy to overlook despite its abundance on Earth.
• 🌊 Over 70% of the Earth's surface is covered in water, cycling continuously between oceans, rivers, and the atmosphere.
• 🚰 About 60% of the human body is composed of water, making it essential for life on Earth.
• 🪐 Liquid water is rare in the rest of the solar system, highlighting Earth's unique abundance of this resource.
• ☄️ Water molecules, composed of hydrogen and oxygen, formed in the universe through nucleosynthesis in stars and were spread by supernovas.
• 🌌 Some of the water on Earth may have originated from icy comets or asteroids that bombarded the planet after its formation.
• 🌋 The Earth's first atmosphere, formed through a process called outgassing, helped trap water on the planet's surface.
• 🪨 Recent studies of carbonaceous chondrite meteorites suggest that Earth may have retained significant water early on, even without a substantial atmosphere.
• 📅 This early presence of water implies that life on Earth could have potentially formed earlier than previously believed.
• 🌌 Whether Earth’s water came primarily from its initial formation or from later impacts remains an open question, emphasizing the cosmic journey water has undergone.

Q & A

What percentage of Earth's surface is covered by water?

Over 70% of Earth's surface is covered by water.

How much of the human body is composed of water?

About 60% of the human body is made up of water.

Why is liquid water rare in the rest of the solar system?

Liquid water is rare in the rest of the solar system due to the conditions necessary for its existence, such as temperature and atmospheric pressure, which are difficult to find on other planets.

How did hydrogen and oxygen, the components of water, form in the universe?

Hydrogen has been present since close to the beginning of the universe, while oxygen formed several hundred million years later through nucleosynthesis in stars.

What role do supernovas play in the creation of water?

Supernovas spread elements like oxygen across the universe, which then combined with hydrogen to form water molecules.

What is one theory about how Earth initially acquired its water?

One theory suggests that small amounts of water were present when Earth formed, but high temperatures and the lack of an atmosphere caused the water to evaporate into space.

How did Earth's atmosphere contribute to the retention of water?

Earth's atmosphere, formed through a process called outgassing, helped trap water by creating a layer that prevented water from escaping back into space.

What is the theory that asteroids brought water to Earth?

Scientists suspect that much of Earth's water was brought by ice-bearing asteroids that bombarded the planet over millions of years.

What recent evidence challenges the theory that water arrived primarily from asteroids?

Recent research on carbonaceous chondrite meteorites shows that they contained water and had a similar composition to Earth’s rocks, suggesting Earth accumulated substantial water early on.

Why is understanding the origin of Earth's water important for understanding life on the planet?

If Earth’s water accumulated early on, it suggests that conditions for life may have formed earlier than previously thought, providing insight into the timing of life’s emergence.