Lecture 1 - Origins of the Oceans

When did the Big Bang occur (creation of the universe)?

13.8 bya

When did Earth form?

4.6 bya

What is a galaxy?

A rotating system of stars, dust, gas, and other cosmic material held together by gravity.

When did the first galaxies form?

After the first stars formed after the Big Bang.

What is the lifecycle of stars?

1. Nebula

2. Condensation/

3. Nuclear Fusion

4. Supernovae

What is a nebula?

A cloud of gas and dust where stars are born

What is the process of condensation during the formation of a star?

Gravity pulls material together to form a young star (protostar)

What happens during nuclear fusion in a star?

Hydrogen atoms combine to form helium, releasing large amounts of energy as light and heat.

What happens when a star becomes a supernova?

When a star dies, it can explode in a supernova, creating and spreading heavier elements throughout space.

What percentage are we formed by stars, by mass?

90%

What is accretion?

The gradual clumping together of dust, gas, and small particles into larger bodies (planetesimals).

What is the formula for density?

Mass/Volume

How did Earth become density stratified?

Heat from accretion, impacts, and gravitational compression partially melted the early Earth, allowing dense materials to sink and lighter materials to rise, forming Earth’s layers.

How did the moon form?

A Mars-sized object (Theia) collided with the young Earth, ejecting debris into space. The debris eventually came together to form the Moon.

How did Earth’s first oceans form?

Water vapor in the atmosphere cooled and condensed into liquid water.

What is the oxygen revolution?

A major increase in oxygen in Earth’s atmosphere about 2 bya.

Trace the history of seawater with these keywords:

• Heavier elements

• Atmosphere

• First Stars

• Ocean

• Accretion

• Big Bang

• Earth

• Supernova

• Condensation

• Solar System

• Oxygen

• Hydrogen

1. Big Bang

2. Hydrogen

3. Condensation

4. First Stars

5. Oxygen

6. Supernova

7. Heavier elements

8. Solar System

9. Accretion

10. Earth

11. Atmosphere

12. Ocean

Which is the most abundant element in the universe?

Hydrogen.

How are the heaviest elements (i.e. oxygen, carbon, iron) created in the universe?

• Created inside stars through nuclear fusion

• During supernova explosions when stars die

How old is the solar system?

4.6 byo (like Earth)

Where did Earth’s current atmosphere and oceans come from?

Outgassing

What are the most abundant gases in the Earth’s current atmosphere?

• 78% Nitrogen

• 21% Oxygen

• Small amounts of argon, carbon dioxide, and other gases.

Where can you find liquid water outside of Earth?

Beneath the icy surfaces of some moons (Europa and Enceladus).

What elements formed immediately after the Big Bang?

Hydrogen and Helium (the lightest elements)

What process formed Earth and the other planets?

Accretion

Where did the water vapor that formed Earth’s first oceans come from?

Most water vapor came from outgassing (volcanic activity), which released water and gases from Earth’s interior into the atmosphere.

Besides outgassing, how else may water have been delivered to Earth?

Some water may have been delivered by icy comets and asteroids that impacted the early Earth.

What caused the Oxygen Revolution?

Photosynthetic organisms