Geology Reference
In-Depth Information
wise,allowyourimaginationtoskipbackseveralbillionyearsintothepast,whenourplan-
et was born.
The birth of Earth 4.5 billion years ago was a drama that has been repeated countless
trillions of times throughout the history of the universe. Every star and planet arises in the
tenuous near-vacuum of space from gas and dust—individual particles of matter too small
to see with the unaided eye, yet so vast in total extent that we can observe immense star-
forming clouds halfway across the galaxy. Billions of years ago, gravity served to midwife
theSolarSystem'sbirth—theSunemergedasthesolitarygiantinalitterofplanetaryrunts.
Nuclear reactions inflamed the Sun's surface, bathing its planetary neighbors in light and
warmth. And so our home took its first halting steps to becoming a living world.
As alien as such epic events might seem, we all experience, every day of our lives, the
same cosmic phenomena that led to Earth's formation. The very same elements and atoms
that forged Earth also make up our bodies and our dwellings. The same universal force of
gravitythatassembledthestarsandplanetsfromdustandgas,andthatforgedtheelements
into stars, also holds us fast to our planetary home. When it comes to the universal laws of
physics and chemistry, there is nothing new under the Sun.
The lessons of rocks, stars, and life are equally clear. To understand Earth, you must di-
vorce yourself from the inconsequential temporal or spatial scale of human life. We live on
a single tiny world in a cosmos of a hundred billion galaxies, each with a hundred billion
stars. Similarly, we live day by day in a cosmos aged hundreds of billions of days. If you
seek meaning and purpose in the cosmos, you will not find it in any privileged moment or
placetiedtohumanexistence.Thescalesofspaceandtimearetooinconceivablylarge.But
acosmos boundbynatural laws that lead inevitably,inexorably toauniverse that promises
the possibility of knowing itself, as scientific study inherently suggests, is a cosmos that
abounds with meaning.
