Other moons have been discovered that are covered in interesting chemistry.
This is the moon Titan, another moon of Saturn.
The Huygens probe landed on the surface of
Titan a few years ago and took these images.
Showing surface of Titan covered in these rocks.
These rocks are actually made of ice,
icy water.
But they're in an environment that's very different from
one that you and I may be familiar with.
Here, the rivers are made of liquid
methane and other types of hydrocarbons like ethane.
This an alien world, but an alien world full
of organic chemistry, which might tell us something about the
early evolution of life on the Earth and how
organic chemistry gives rise to the building blocks for life.
This is a promising location for
astrobiologists to understand the chemistry
that's necessary for early pre-biology.
And I think it's true to say, and this is not
an exaggeration, but the most
extraordinary development in astrobiology over the
last two decades, has been the search for planets around other
stars, and particularly recent searches for Earth like planets around other stars.
This is one of the holy grails, if you like,
of astrobiology to find a second Earth orbiting another star.
In recent years most of the planets that have
been discovered are too hot, they're too close to their
star or they're too large, they're gas giant planets
that don't have rocky surfaces, necessary, we think, for life.
But in the last couple of years, planets
are being discovered around other stars, the size
of the Earth or slightly larger than the
Earth, that may have conditions suitable for life.
The search for Earth-like planets around other stars is surely
one of the most incredible developments in astrobiology in recent years.
And one of the most extraordinary vindications of that early speculations
by Giordano Bruno about the possibility of numberless Earths orbiting other stars.
So what have we learned in this lecture?
We've learned that despite everything we hear about astrobiology
being a new science, it's actually an ancient science.
That began in the philosophical schools of ancient Greece.
It's only recently it's become very
scientifically constrained with new missions and
spacecraft that have allowed us to study the surfaces of other planets
and new studies of ancient rocks that have allowed us to study
the possibilities of early life on Earth and how life first originated on
our planet.
We have also learned there are several
planetary bodies in our solar system that have
become of interest in the search for life and we'll be explored in future years.
We can now hunt for Earth-like planets around other stars in
our galaxy, opening up vast realms of space to astrobiologists to
search for life, and study whether the experiment in biological evolution
that has occurred on the Earth, may have occurred somewhere else.
I think we can say without
a shadow of doubt, the future will hold many remarkable
discoveries and surprises in this rapidly developing field of astrobiology.
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