In order to undersand our position in the universe,
I am going to show you something that has elaborated the ESA, specially to understand
a little bit the distances. We are going to star by placing our position on Earth,
the Himalayas and we raise over the Earth and move away from it.
When we move above the surface of the Earth some kilometres we can see that it is not flat.
We know it is spheric and not flat.
In fact, it is a tiny part of universe, because it is so small and the universe is very cold and dark.
Here we are going over the flatland of Tibet and now
we start to see the whole Earth with its plendour.
The Rosetta spacecraft, which is now a lot of millions of kilometres far away from the Earth and
observed the Earth in this way many years ago and it observed that the Earth
is not alone in the universe. It has a lot of elements around it that
human beings have placed there, for instance satellites. These satellites
allow us to know what is happening on Earth and it helps us for example
landing in national airports with that GPS, but they also
conform a problem for traffic.
If in the future we had to move in the space, to go to other planets
corssing that barrier of satellites could be
a problem. Well, with a distance of a second,
light will last one second to arrive the orbit of the Moon. The orbits of
inner planets we can see here
Venus, Mercury...are just a few minutes away.
We can move away from the external orbits in approximately some hours
Here light would have travelled for a day and we find Oort cloud, which is
the origin of those comets that now are being oberved by Rosetta spacecraft. As we move
approximatelly a year, we can see the first stars.
So the first stars are a year light.
The quantity of emissions in electromagnetic waves
by human beings has reached distances of some tens of years light from us.
The size of the Milky Way has around 100.000 years light of distance
and we can move away as we can see very quicky using the
speed of light to distances that are millions years light from the Earth and they conform our group.
Now we have moved away from our galaxy and we start to see a group of galaxies
until distances of the order of thousands of millions of light, comparable to the
age of the own Earth 5.000 millions of years light, in English a thousand millions.
Well, the structure we can see here is formed by
the galaxies we can measure. It is done by the catalogue of the Sloan Digital
Sky Survey and it allows us to know and set in the space
these galaxies. All of this is the sphere of far universe with a background of radiation of 13,700 millions of years.
And now we return again to the Earth.
You have seen the visible horizon and there was a question "what is beyond
that visible horizon?" and I am going to try to describe it in this lecture.