In 2013 the European Space Agency
launched a rocket from a launch site in
French Guiana and travels some 1.5
million kilometers to reach its
destination in orbit around the Sun. The
spacecraft is called Gaia. Its mission is
to make the largest, most precise
three-dimensional map of the Milky Way
ever attempted.
The science behind Gaia was
recognised by everybody right from the
start of something that that mankind
must do.
Gaia is going to be a revolution
in fundamental astronomy. It's going to
be a mission that's going to affect
everything in astronomy.
Gaia is going to
produce tomorrow's version of all the
great star catalogs that have gone back
in history to the very dawn of astronomy
so it's our chance to understand how
nature actually put together our night sky.
The Milky Way the galaxy in which
planet Earth sores around the Sun at
67,000 miles per hour, is so vast that it
takes a beam of light 100,000 years to
travel across it.
It is home to more than
100 billion stars and maybe as many
planets.
It includes such exotic phenomena as
star clusters,
supernovae,
gas clouds,
supermassive black holes
and an elusive substance called dark matter.
But it's not just those stars ablaze
with nuclear fusion at their burning
heart that we're interested in. Gaia is
also looking for failed stars -  brown
dwarfs. Stars that never truly ignited
and a left adrift across space as
interstellar itinerants.
It will also provide an inventory of our
solar systems asteroids and comets. From
the near-earth objects to those located
in the farthest frozen reaches of the
outer solar system.
Revealing exoplanets as well as objects
that could pose a threat to life here on earth.
On the 25th of April 2018, detailed
information on more than a billion stars
will be made freely available to anyone,
anywhere in the world. This is the second
major data released from Gaia based on
22 months of observations and about half
a trillion individual measurements. It
will be the richest star catalog to date
including high precision measurements of
the positions, distance indicators and
motions of 1.7 billion stars and will
lead to a huge number of discoveries
about our home galaxy.
So what are the
personal hopes and expectations for the
Gaia mission, a mission 30 years in the
making.
We're going to be able to walk
through the universe and we're going to
realise just exactly what we are
compared to other people. We're going to
find tens of thousands if not hundreds
of thousands of other planetary systems
some of which we like our own quite
close we'll be able to take pictures of
those planets. We're going to discover
the things we can't see the Dark Matter.
We will go beyond what we can see to be
able to understand reality and I think
this is exactly the same transition that
Captain Cook made, we go beyond our
preconceptions to see hey this is what
the world is like guys and we'll be able
to just walk through it.
We will see the remnants,
the debris streams of the
first shards that became what is today
the Milky Way. We can run the process
right back to the first things that ever
happened. We will see the entire history
of the Milky Way unfolding before our eyes.
We're going to discover completely new things.
We're going to discover that
stars are moving in ways that we think
are impossible and so we're going to
learn completely new things about what
happens. We're going to discover that
there's actually an awful lot of matter
there and hardly any there and we'll be
able to say well what is it then?
How is that possible? So we'll learn a
lot about elementary particle physics
and possibly even about theories of
gravity so I think that's going to be
the real dramatic change. The stuff
that's going to kind of come out of Gaia
is not the spectacular science that we
know it's going to do.. it's the stuff
that we don't, the questions we don't
know how to answer.
