Posted on Thursday, February 06, 2014
Young Sun, Early Earth and the Origins of Life by Muriel Gargaud, Hervé Martin, Purificación López-Garcia, Thierry Montmerle and Robert Pascal
Rating: 9/10
Carl Sagan wrote in his book “Cosmos”
: “If you want to make an apple pie from scratch, you must first
invent the universe.”
This book about astrobiology is written
in a way that seems to be following Carl Sagan's thought.
This far the only example of life we
have is the one now present on Earth, in the Solar System. As usual
in a system objects interact with each other and so it's important to
look at the whole system to understand more about the parts of it.
The book starts with the formation of
the Sun, some 4.7 billion years ago in a molecular cloud that the
young Sun shared with many other stars that have left the Sun's
vicinity since that time. First we learn about the stars, how they
form and evolve and how the stars initial mass affects how long the
fusion processes in the star will keep going.
As it is now known many stars have
planetary systems and explaining how the planets form is the next
step on the way to finally understanding the necessities for life.
Nowadays, when some stars have been
observed with the protoplanetary disks (Vega in the constellation
Lyra, having been the first), scientists understand planet formation
better than they did about a hundred or even just fifty years ago,
when one of the theories for planet formation involved a giant comet
passing by the sun really close and tearing away gases from the Sun
that would eventually lead to the planets forming.
In the present it is thought that the
planets form from the same disk of left-over mass around a star that
will be sticking together ass time passes and they'll start forming
little chunks of matter, that through numerous collisions will
eventually become protoplanets. There are some questions still in the
theory as collisions of larger objects tend to rather break the
objects apart than combine then in an even bigger object.
However we end up having a planetary
system and now we get to the planet Earth, and it's geologic history,
what kind of processes were taking place on Earth billions of years
ago – how would it have looked like on Earth during the Heavy Late
Bombardment, the scars of which can still be seen on the Moon, and
when did Earth actually have conditions that might have been suitable
for life to evolve.
It is an interesting read as
astrobiology combines research in so many different areas such as
biology, chemistry, geology and astronomy, and while the book starts
with astronomy, it continues on with geology and such interesting
topics as how the Earth's crust has formed – although the formation
of the oceanic and continental crust is a topic that is covered in
high-school and sometimes even middle-school geography or Earth
science lessons, then it's taught as it is happening in the present,
but not how the processes were in the beginning of the Earth's
geologic history – since the conditions were different, then even
the crust that formed was not the same as it is now.
We also find out about the atmosphere
on the early Earth, and how do scientists even get information about
it. Also the environment on Earth was very different in other ways as
well, not just in the atmosphere's content – the internal energy
generated inside the Earth was about four times as much as it is now,
but the Sun was about 20% fainter.
So how is it that we've ended up with a
planet with exactly this kind of atmosphere and life and a average
global temperature of about 15 degrees centigrade? Now we also dive
into molecular biology and chemistry to find out how can organic
molecules form in certain conditions, and how did RNA evolve and how did the simplest life forms evolve into more complex
life.
We also go through some catastrophic
events on the Earth such as asteroid impacts and ice ages and
glaciation, which seemingly brings as to the present time.
The book ends with an exploration of
the topic of exoplanets and which are found monthly now of various
sizes and characteristics.
Overall this book is a great source of
information that nicely links up everything that you need to know
about in astrobiology, and it's accompanied by many schematics and
illustrations that help a lot in understanding the text, as well it
comes with a very helpful glossary in the end of the book.
Labels: astrobiology, book review