2B-1

Topic 2B:The Nature of Science

and Origins of the Ocean,Part II

Lecture:The Origin of Water & the Oceans

The Formation of Atoms, Molecules, the Earth, the Atmosphere, and the Oceans.

2B-2Hubble Space Telescope looking at our own galaxy

There so many stars in our galaxy…

2B-3GalaxiesThe Universe:over 50 billion galaxies,

each with over 50 billion stars

Galaxies

2B-4

○ Observation:the farther away from us a cluster of galaxies is,the faster it is moving away from us– in the past, galaxies were

closer to one another– at one time, were all together

(approximately 14 billion years ago)

Example: Origin of the Universe

What can science say about what happened before

the “Big Bang”?

Earth bathed in microwaves:

“echo” (TV static)

2B-5How do we know what stars and nebulae

are made of?

“Spectroscopy”

Every substance has a “light fingerprint:”it absorbs and emits

certain specific shades of each color

2B-6Gravitational attraction pulled togetherthe hydrogen and helium leftover from the Big Bang to create stars like the Sun

2B-7Nuclear Fusion inside Stars

○ Hydrogen and helium are the two smallest atoms.○ The enormous temperatures and pressures inside stars

cause small atoms to join (fuse) and become larger atoms.– Oxygen, carbon, silicon,

sodium, iron, and all the other large atoms are made from smaller atoms fusing together.

○ The fusion of small atoms into bigger ones releases a lot of energy. – This energy powers stars,

creating the light they send out.

2B-8

Planetary Nebula

Supernovae Remnants

Nebula

Clouds contain water, organic molecules, etc.

Stars explode in “Supernovae,”creating dusty clouds

2B-9Water in Our Solar System

CometsAsteroid

Saturn’sRings

Mars’Poles Europa

How is water on Earth different from water elsewhere?

Telescopes show us that water is quite common in the universe

Enceladus

Pluto is 33-50% ice.

2B-10

Formation of the Solar System & the Earth

Gravitational attractionpulls nebula together

Nebula

2B-11

The Early Earth was very hot

2B-11

2B-12Age of the Earth: Radiometric Dating

Moon

Meteor

Age of the Earth:4.5 billion years old

Crater

2B-13Where Did the Water in the Oceans Come From?

VolcanoesComets

Which hypothesis seems more likely based on the

observations that we have?

2B-14Why is the Ocean Salty?

Organisms’ BodiesBecome Sediments

Rivers Hydrothermal Vents

add salts(!)

remove salts

add some salts,remove other salts

2B-15The Fossil Record

○ Fossils are the remains of living things:bones, impressions (tracks, skin, feathers), dung, etc…

○ An incomplete & imperfect record of life in the past,so one must be careful when interpreting the fossil record

– new discoveries are constantly filling in gaps

– remains of some organisms are preserved more easily than others

If we find more fossils of shelled animals than “jellies”, should we conclude that there

were more shelled animals than “jellies?”

2B-16Fossils in Sedimentary Rocks

2B-17The Fossil Record IISpecific layers of the rocks contain specific fossils

Older rock is on the bottom

2B-18The History of Life on the Earth

First Appearance in the Rocks Age of Rocks

Winged Insects, Reptiles ≈ 300 million years ago

Seed plants, amphibians ≈ 350 million years ago

1st Life on Land ≈ 440 million years ago

Shelled organisms ≈ 540 million years ago

Multi-cellular Organisms ≈ 2.1 billion years ago

Single-Celled Organisms ≈ 3.4+ billion years ago

Order inferred from layers in sedimentary rocks. Time based on radiometric dating

(which also confirmed the order).

2B-19Earliest Life: Bacteria who lived in the ocean

Stromatolites

Fossils of Stromatolites

Oldest Fossils:3.5 billion years old

Fossilized Cyanobacteria

Stromatolite Fossils

Stromatolites in Australia Today

Earliest Life3.5+ billion years old

2B-20

AmmonitesEurypterid

Dorudon

Trilobite

Life started in the Ocean, and stayed there for most of the Earth’s History

Hallucigenia

2B-21The Atmosphere: now mostly nitrogen & oxygen

Comets

water vapor,carbon dioxide,nitrogen, etc.came out of volcanoes

photosynthesizing bacteria

transformed the carbon dioxide

into oxygen

Stromatolites

cyanobacteria