Spaceship Earth Week 31 Earth in the galactic vastness


We’re now here, between
the summer solstice and the autumn equinox which we will be reaching in 8 weeks. In the cities,
increasing pollution and light prevents us from seeing the night sky. Even when the weather is fine
we see only the brightest planets Venus, Jupiter, sometimes Mars
and the brightest of the stars, Sirius, which can be seen in the evening,
especially in winter, the constellation of Orion
and naturally, the stars nearest the zenith the Great Bear/the Big Dipper,
and the pole star stars farthest away
from the glow of the horizon. When you leave the city on holiday,
find somewhere where there are no lights. There, from 11pm on,
you can see our galaxy, the Milky Way, a pearly haze
formed by the mass of distant stars. Our galaxy is an enormous disk made of
200 billion stars, all the visible stars, including our Sun. We see only some of them because
we’re inside this disk ourselves. Our galaxy is 100,000 light-years wide. That means light takes a 100,000 years
to cross the galaxy. The Galactic disk carries us along
at a million km an hour. Just imagine.
1 million kilometers every hour! That’s 10 times faster than
the speed of the Earth in orbit. Let’s compare the galaxy with
the dimensions of the Earth and solar system. Since they formed, the Earth and Sun
have been round the galaxy only 20 times. We could say they are 20 galactic years old
and that’s young. Our galaxy is shaped like a spiral because
the stars on the outside of the disk are lagging behind. Beyond our Milky Way,
space opens onto other galaxies billions of them. The galaxies are moving apart.
In fact they’re all moving away from the same starting point,
the original explosion, the Big Bang, which we believe, created the universe
12 to 15 billion years ago. In a fraction of a second
the Big Bang released enormous energies which still power the universe today. Don’t bother asking what was there
before the Big Bang happened? There was nothing because
the Big Bang created time and don’t bother asking
what was in space outside the Big Bang. Nothing, because
the Big Bang created space too. So there’s no before and no outside. Since the Big Bang,
the galaxies have been moving apart because the universe is expanding
like an inflating balloon. Every spot
on the surface of an inflating balloon is moving away from every other spot. The galaxies are all flying apart
like that. The further away they are,
the faster they move. That gives us an astonishing perspective. From our viewpoint
all the galaxies seem to be moving away. We see the universe expanding
as if we were at its very center. This viewpoint is just as true
just as real as the perspective as someone looking at the universe
from the point of the Big Bang. We really see the universe expanding
as if we were at its center. Yet, without realizing it,
without feeling it, we are part of this galactic flight. We are caught up
in the rotation of the Milky Way which carries around the Sun,
which carries around the Earth, which carries us around with it. Does that mean we are just dust particles
lost somewhere in the vast universe? Not necessarily. If you observe the universe
you become its central point even if this central point isn’t fixed
in one place. The entire solar system
is moving inside the galaxy. Over millennia, the Sun, accompanied by
its 9 planets, Earth included, has been heading in the direction of Vega
above Scorpio. So after a year, the Earth doesn’t reach
the place it occupied 12 months before. It follows the Sun’s drift
through the galaxy. If we visualize the route
the Earth has taken its annual circular
orbit around the Sun stretches out into a spiral through space. And like all the universe
the Earth moves through another dimension time. In a year
the Earth draws its circle around the Sun. From year to year, the Sun and Earth
move forward through time. The circle stretches out into a spiral. This picture of time matches & even merges
with the Earth’s movement in space. And like any other picture
this picture of time needs space like the space on your TV screen
right now.

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