Hello, and welcome. 
I'm Charles Cockell, Professor of 
Astrobiology at the University of 
Edinburgh. And thanks for taking this 
course, Introduction Astrobiology. 
Astrobiology is a very new, exciting, and 
a very rapidly developing area of science 
that addresses the question of the 
origin, the evolution, and the 
distribution of life in the universe. 
There's little doubt in saying that one 
of the most exciting questions in 
Astrobiology Is are we alone in the 
universe? And I should say right at the 
beginning of this course we don't have an 
answer to this question, but we do know 
that the answer is either yes or no. 
And either one of those answers has 
profound implications for our 
understanding of our own place in the 
universe. 
If the answer to this question is yes we 
are alone in the universe, then we need 
to ask the question. 
While we are learning the universe. 
What is missing on other planets that was 
present on Earth and allowed life to 
originate and evolve here? We would have 
to find out about the origin and the 
evolution of life on Earth in order to 
find out why life on Earth is so special. 
It would also raise fundamental 
philosophical questions. 
If there's no other life in the rest of 
the universe there's no one else to talk 
to. 
Then why have we spent the last 40,000 
years building a civilization. 
Is it just so we can be lonely in greater 
luxury? Astrobiology forces us to Address 
philosophical questions that strike at 
the very core of our civilization. 
If the answer to this question is no, 
we're not alone in the universe, we're 
also faced with some very fascinating 
questions. 
What is the nature of this other life on 
other planets? Is it microbial life? Life 
like bacteria and if so how does it 
compare to life on earth and where is it? 
Or is it intelligent life? And if it is 
intelligent life what is the nature of 
this other intelligence. 
Can we communicate with it, and what will 
be the consequences if we do communicate 
with it. 
All that we know in the universe is 
unquestionably. 
The, the one question in astro biology 
that fires the imagination of the general 
public. 
And it's probably the question that 
brought you along to this course. 
It's a very reasonable question to ask 
when you think about the universe that we 
live in. 
The planet on which we live orbits a 
single star, and this star. 
Is one of about 200 billion stars in the 
Milky Way galaxy. 
And our own galaxy is probably one many, 
many billions of galaxies throughout the 
universe. 
In truth we don't know how many galaxies 
there are in the universe. 
It may be something on the order of 100 
billion galaxies, maybe more. 
But if you think about it, 200 billion 
stars in our own galaxy. 
Possibly a 100,000,000,000 galaxies 
throughout the universe. 
It seems reasonable to ask the question, 
is there life on other planets? And, that 
is why astrobiologist concerned with a 
question for which we do not yet have an 
answer but which scientifically 
impirically looks like a reasonable 
question to ask. 
To search for life on other planets, we 
first of all have to understand something 
about life on our own home planet Earth. 
This is a rather beautiful image taken by 
the Apollo 11 astronauts on the surface 
of the Moon and it shows the Earth 
hovering above the horizon of the Moon. 
It's sometimes called the blue marble 
image. 
Because it shows a picture of the earth 
as a tranquil planet. 
It looks like a very peaceful place but 
this belies the history of life on earth 
and the future of life on this planet. 
For example, we know that planet earth 
has been struck by large pieces of rock 
in it's past. 
Asteroid and comet impact that have done 
devastating things to life on the surface 
of the earth. 
We think, for example, that the dinosaurs 
were made extinct by such an asteroid 
impact 65,000,000 years ago. 
Now, whether an asteroid really did kill 
the dinosaurs. 
It's something that's controversial in 
some parts of the scientific community, 
but whatever one views about The fact 
that scientists purport that the 
extinction of the dinosaurs was caused by 
an asteroid shows that, for in order to 
understand the past history of life on 
earth, we have to understand it's 
connection with the cosmic environment. 
What sort of rocks might come from outer 
space and threaten life on the earth. 
So, to undrstand past history of life on 
earth, we have to understand Astropology, 
how life fits in to its cosmic 
environment. 
We also know that the future of life on 
earth is going to change. 
This is a rather dramatic image of the 
cloud Nebula, the result of a supernova 
explosion, an exploding star which 
exploded thousands of years ago. 
Our own Sun may not end its life in quite 
such a dramatic matter. 
But in a few billion years from now sun 
will come to the end of it's life and at 
that point our own planet will be 
completely destroyed and all life on will 
be extinguished. 
That's not for a long time to come but we 
do know that in order to understand the 
future of life on a planet. 
Its long term future. 
We must think about the connection of a 
planet. 
Again, with its cosmic environment. 
How it connects with the history of its 
parent star. 
And how long that star lives. 
And therefore, how long you can expect 
life to survive on a planet. 
So in order to understand life on Earth, 
we have to understand the past history of 
life, and its connection with the cosmic 
environment. 
And we have to understand. 
The future of life on earth and it's 
connection with the cosmic environment. 
In other words, an understanding of life 
on earth is really about studying 
astrobiology, the connection of life with 
it's astronomical or cosmic environment. 
So astrobiology has many areas that we 
will look at in this course and many 
questions that it wants to address. 
Let's have a look at some of these 
questions, and see what we're going to 
look at throughout this course. 
Astrobiology is first interested with 
understanding the origin of life on this 
planet. 
How did it come about? And the sorts of 
questions that astrobiologists ask, and 
that we'll be looking at in this course, 
how did life originate on this planet? 
Where did life originate? What were the 
locations of the first organisms to 
emerge on this planet? Where might they 
have first evolved? Is life an inevitable 
process? On any planet where the 
conditions are good enough, do you always 
get an evolution of life? Is this a 
common process? Throughout the universe. 
When did this happen? Did it happen very 
quickly after the Earth was formed or did 
it take rather a long time for those 
chemical reactions to lead to the 
earliest types of life. 
And what is the evidence for the origin 
of life on this planet and it's emergence 
into early single cell organisms that 
first occupied this planet many billions 
of years ago? Once we've established the 
presence of life on a plant we want to 
know its limits. 
How far can you push it and what sort of 
extremes can it live in. 
This is important if we're to try and 
understand the possibilities of life on 
other planets to access that habitability 
as we call it. 
And the sorts of questions that 
astrobiologists want to address are. 
What are the limits of life? What are the 
most extreme physical and chemical 
environments that life can survive and 
grow in? How does life survive extremes? 
What are the sorts of mechanisms that it 
involves? What sort of biochemistry, what 
sort of physiology do organisms evolve in 
order to be able to cope with some of the 
most extreme environments on the earth? 
And are these limits universal? If we do 
find life on another planet out there in 
the universe, will it be living in 
completely conditions from life on Earth? 
Or will we in fact find similar life 
living in similar types of environments. 
And once we've looked at life in extremes 
what does that tell us about the 
prospects of life elsewhere, about the 
possibilities for going to extreme 
environments on other planets and finding 
life there? So by studying life on our 
planet today and looking at the way in 
which it lives in different types of 
environments and different extremes. 
We can learn something about the 
prospects for life elsewhere. 
Astrobiology, as I've already mentioned, 
is also concerned with trying to 
understand the history of life on Earth 
once it did emerge. 
It's concerned with questions like, how 
is life related? When you walk around 
outside you see a whole diversity of life 
from dogs to giraffes to trees. 
How are all these different creatures 
related and how do they come to be on the 
surface of the earth and how did they 
evolve? Astrobiology is interested in 
trying to understand the connection 
Between these different creatures and how 
they came to be and evolve from one 
another over time. 
We also want to know about multi-cellular 
life, complex life. 
We'll see later in this course that when 
you look around you most of the life that 
you and I are familiar with are things 
like. 
Dogs and giraffes that are multicellular 
creatures, complex large organisms that 
we can see with the naked eye. 
But in fact much of life on Earth is 
bacteria, archaea, simple single celled 
organisms. 
And we want to understand as 
astrobiologists how life emerged from 
those more simple organisms in the early 
history of life on Earth, to the more 
complex life that you and I see on a 
day-to-day basis. 
On the surface of the planet. 
And another question that concerns 
astrobiologists is catastrophes and 
extinctions. 
How does life go extinct? How do these 
catastrophes affect life throughout its 
history whether that be asteroid or comet 
impacts, giant volcanic eruptions, and 
what sort of catastrophes might befall 
life along its long tenure of life on 
earth? Astrobiology is concerned with 
taking this information and looking for 
life elsewhere. 
And as I said earlier there's no doubt 
that this is most interesting question in 
astrobiology. 
At least the one that captures the public 
imagination. 
And the sorts of questions that 
astrobiologists ask once they begin to 
get an understanding of life on the Earth 
is. 
Is there life elsewhere in the universe? 
Are we a unique experiments in biological 
evolution or is it repeated on other 
planets? And if there is life elsewhere, 
what does it look like? What sort of life 
is it? Is it microbial life, single 
celled life or is it intelligent life? 
And if there isn't any life out there in 
the universe Why not? What's missing in 
the rest of the Universe that was present 
on the Earth that allowed life to 
originate and evolve on this planet? Of 
course, following on from that question, 
another interest for Astropology but 
certainly for the general public. 
Is, are there other intelligences in the 
universe. 
If there is life out there, could it be 
intelligent life. 
And the source of questions that 
astrologist want to address is, is 
intelligence inevitable. 
Whereever we get life on a planet is it 
inevitable that it will eventually 
progress to intelligent types of life 
forms. 
Can we communicate with life on other 
planets, and if we do communicate with 
it, what would be the consequences for 
society. 
What would happen to us if we made 
contact with another intelligences. 
How would that affect religion and our 
social structures, and we'll answer some 
of those questions in this course. 
Of course it's all very well looking for 
alien life and studying the evolution of 
life on the earth and going out hunting 
for life elsewhere. 
But of course we may eventually ourselves 
leave the Earth and travel beyond and 
establish permanent settlements on places 
Like the moon and Mars. 
And astrobiology is also concerned with 
the technical question of how human 
beings will establish themselves in 
space. 
What is the future of human life beyond 
the Earth? The sorts of questions that 
astrobiologists are concerned with span 
from science, to technology, to 
philosophy and these. 
Sorts of questions are things like will 
humans leave the Earth? Is it inevitable 
that we will move out beyond the Earth 
and establish a permanent human presence 
beyond our home planet? And if we do make 
this choice to leave the Earth how will 
we do it? How will we establish 
self-sustaining settlements on other 
planets? And if we are going to spend 
money and human resources establishing, 
other branches of civilization, beyond 
the earth on other planets, how do we do 
that but at the same time preserve the 
earth? How do we look after our own 
planet, live sustainably on the earth, 
but establish sustainable settlements on 
other planets. 
And planetary bodies such as the Moon and 
Mars. 
And how will we adapt to space if we move 
out beyond the what will be the social 
implications for humanity. 
How will we change as a species? How will 
our societies develop as we move out 
beyond the Earth and establish satellites 
on other planetary bodies? These are just 
some of the questions, some of the 
Diversity of questions that 
astrobiologists seek to ask. 
And in this course you're going to learn 
a number of things. 
You're going to learn about basic 
concepts that underpin the study of 
astrobiology, some of the questions that 
I've just described to you. 
We're going to learn about some of the 
history of life on our home planet, how 
it originated, how it evolved. 
We're going to learn about how we search 
for life on other planets, how we use our 
knowledge of life on the earth to go. 
Beyond the Earth and send out missions to 
Mars and other planets and seek out 
signatures of life on other planetary 
bodies. 
We're going to look a little bit about 
the future of human life beyond the Earth 
and the establishment of a permanent 
human presence beyond Earth. 
We're going to look at some of these 
social implications. 
Of astrobiology. 
More difficult to define than some of the 
scientific research associated with 
astrobiology, but never the less very 
important for understanding the way in 
which science can affect society. 
And the way in which we think about The 
Universe around us. 
We're also going to look at the 
difference between science and 
sensationalism. 
And you may have noticed that in some of 
the publicity for this course, there was 
even talk about UFOs, alien autopsies, 
and all sorts of crazy, but never the 
less, interesting material that captures 
the imagination of many people. 
And in this course, we want to learn 
about. 
What is empirical size. 
What is evidence that allows us to 
address scientific questions of 
astrobiology. 
On more areas of astrobiology and not are 
depend at the moment by any empirical 
evidence that make it difficult to 
address particular questions. 
Astrobiology is a very good vehicle. 
Particularly when we talk about 
extraterrestrial intelligences, so 
thinking about the difference between 
science and sensationalism and we'll 
touch upon some of those problems 
throughout this course. 
So what have we learnt in this brief 
introduction to astrobiology? Hopefully 
what you've learnt is that astrobiology 
covers many fields. 
It's a very diverse subject. 
It goes from physics, to chemistry, 
biology, and even philosophy and 
sociology when we think about the 
implications of discoveries in 
astrobiology. 
Astrobiology is a subject as its name 
suggests. 
Astrobiology that sets life in its cosmic 
context. 
It seeks to understand how life on a 
planet evolves in the context with 
changing astronomical environment, and 
how life changes through Its origin, its 
evolutional planet, and eventually the 
end of that planet as its destroyed 
perhaps by its parent star. 
Astrobiology seeks to understand life 
from how it arose to how intelligent life 
might one day colonise other planets from 
Earth possibly to the Moon and Mars and 
beyond. 
And as you'll see throughout this course, 
Astrobiology, as well as being a science 
in its own right, is actually an 
outstanding vehicle for learning many of 
the common principles that underpin 
different parts of science. 
It's a way to learn about different 
disciplines as well as to understand the 
possibility of the origin, evolution and 
distribution of life in the universe.