Four ways to understand the Earth's age - Joshua M. Sneideman

A idade da Terra en medidas que podes entender - Joshua M. Sneideman

Translator: Francisco Caamano Reviewer: Xusto Rodriguez

How old is the Earth?

Cal é a idade da Terra?

Well, by counting the number of isotopes

A ver, contando a cantidade de isótopos

in a sample of rock

nunha mostra de roca

that's undergone radioactive decay,

que sufriu desintegración radioactiva,

geologists have estimated the Earth's birthday,

os xeólogos estimaron os anos da Terra,

when it first formed from a solar nebula,

cando se formou a partir dunha nebulosa solar,

to be 4.6 billion years ago.

en 4.600 millóns de anos.

But just how long is that really?

Pero, canto tempo é iso en realidade?

Here's some analogies

Velaquí unhas analoxías

that might help you understand.

que poden axudarche a entendelo.

For example, let's imagine the entire history of Earth

Por exemplo, imaxinemos que toda a historia da Terra,

until the present day

ata hoxe,

as a single calendar year.

como un só ano.

On January 1st, the Earth begins to form.

O 1 de xaneiro a Terra comeza a formarse.

By March 3rd, there's the first evidence

O 3 de marzo aparece a primeira evidencia

of single-celled bacteria.

dunha bacteria unicelular.

Life remains amazingly unicellular until November 11th

A vida segue incriblemente unicelular ata o 11 de novembro

when the first multicellular organisms,

cando xorden os primeiros organismos multicelulares

known as the Ediacaran fauna, come along.

coñecidos como "biota ediacariana".

Shortly thereafter, on November 16th at 6:08 p.m.

Pouco despois, o 16 de novembre ás 18:08

is the Cambrian Explosion of life,

acontece a explosión cámbrica da vida,

a major milestone,

un fito importante,

when all of the modern phyla started to appear.

cando empezaron a aparecer os filos modernos.

On December 10th at 1:26 p.m.,

O 10 de decembro ás 13:26

the dinosaurs first evolve

apareceron os dinosauros

but are wiped out by an asteroid

pero un asteroide exterminounos

just two weeks later.

só dúas semanas despois.

On December 31st, the mighty Roman empire

O 31 de decembro o poderoso Imperio romano

rises and falls in just under four seconds.

érguese e cae en menos de catro segundos.

And Columbus sets sail

E Colón levanta áncoras

for what he thinks is India

na busca do que pensaba seren as Indias

at three seconds to midnight.

tres segundos antes da medianoite.

If you try to write the history of the Earth

Se intentas escribir a historia da Terra

using just one page per year,

usando só unha páxina por ano,

your book would be 145 miles thick,

o teu libro tería 232 km de grosor,

more than half the distance

máis da metade da distancia

to the international space station.

ata a Estación Espacial Internacional.

The story of the 3.2 million year-old

A historia do fósil de australopiteco

Australopithecine fossil known as Lucy

de 3,2 millóns de anos, coñecido como Lucy

would be found on the 144th mile,

estaría no kilómetro 231,

just over 500 feet from the end of the book.

a 150 metros do remate do libro.

The United States of America's Declaration of Independence

A Declaración de Independencia dos Estados Unidos de América

would be signed in the last half-inch.

asinaríase no último centímetro.

Or if we compared geologic time

Ou senón, comparando o tempo xeolóxico

to a woman stretching her arms

cunha muller cos brazos estirados

to a span of six feet,

a unha amplitude de 1,80 m,

the simple act of filing her nails

o simple acto de limar as unllas

would wipe away all of recorded human history.

barrería de vez a historia humana rexistrada.

Finally, let's imagine the history of the Earth as your life:

Por último, imaxinemos a historia da Terra como a túa vida:

from the moment you're born

dende o momento en que naces

to your first day of high school.

ata que entras no instituto.

Your first word,

A túa primeira palabra,

a primeira ves que sentaches

first time sitting up,

and first time walking

e os primeiros pasos:

would all take place while life on Earth

todo iso ocorre mentres a vida na Terra

was comprised of single-celled organisms.

estaba composta por organismos unicelulares.

In fact, the first multicellular organism

De feito, o primeiro ser multicelular

wouldn't evolve until you were 12 years old

non evolucionará ata os teus 12 anos,

and starting 7th grade,

ao comezar a ESO,

right around the time

xusto cando

your science teacher is telling the class

o teu profesor de ciencias lle di á clase

how fossils are formed.

como se forman os fósiles.

The dinosaurs don't appear

Os dinosaurios non aparecerían

until three months into 8th grade

ata o terceiro mes de 2º da ESO

and are soon wiped out right around spring break.

e extinguiranse ao acabar as vacacións de primavera.

Three days before 9th grade begins,

Tres días antes de comezar 3º

when you realize summer is over

cando te decatas de que acabou o verán

and you need new school supplies,

e precisas novo material escolar,

Lucy, the Australopithecine, is walking around Africa.

Lucy, a pequena australopiteco, está camiñando por África.

As you finish breakfast

Ao terminar o almorzo

and head outside to catch your bus

e saír para coller o bus,

44 minutes before school,

44 minutos antes da clase,

the Neanderthals are going extinct throughout Europe.

os homes de Neandertal estanse extinguindo en toda Europa.

The most recent glacial period

O período glacial máis recente

ends as your bus drops you off

termina cando baixas do bus,

16 minutes before class.

16 minutos antes da clase.

Columbus sets sail 50 seconds before class

Colón levanta áncoras 50 segundos antes da clase

as you're still trying to find the right classroom.

mentres buscas a túa aula.

The Declaration of Independence is signed

A Declaración de Independencia dos EE.UU. asínase

28 seconds later

28 segundos despois

as you look for an empty seat.

mentres buscas onde sentar.

And you were born 1.3 seconds before the bell rings.

E ti naces 1,3 segundos antes de que soe o timbre.

So, you see, the Earth is extremely,

Como ves, a Terra é sumamente

unbelievably old

e incriblemente antiga,

compared to us humans

comparada cos seres humanos,

with a fossil record

con fósiles

hiding incredible stories to tell us about the past

que gardan historias incribles que contarnos sobre o pasado

and possibly the future as well.

e posiblemente sobre o futuro tamén.

But in the short time we've been here,

Pero, no pouco tempo que levamos aquí

we've learned so much

aprendemos moito

and will surely learn more

e seguro que aprenderemos máis

over the next decades and centuries,

nas próximas décadas e séculos,

near moments in geological time.

momentos próximos en termos xeolóxicos.