|In the words of the late Douglas
Adams (1952-2001), The
to the Galaxy tells us that "Space
is really, really BIG.... you might think its a long way down
the street to the chemist, but that's just peanuts compared to space!"
Yes, the vastness of space does seem mindbogglingly huge to us mere
mortals who, he goes on to advise, inhabit a small, insignificant
blue green planet, circling a star we call the Sun, in an
spiral arm of a galaxy known as the Milky Way.
Light travels at the fastest speed
known to man, at almost 300 million metres per second, 671 million
miles per hour or 5,878,630
million miles per year -
referred to as a 'light year'. I am pointing this out because space is
so vast that beyond our own solar system we measure distances in light
years. It takes 8.3 minutes for light from our
sun to reach the earth - and from our moon, a little over 1 second. Now
to get some idea of scale, our galaxy
contains billions of other stars like our sun and the diameter of our
galaxy is over 100,000 light years across. These figures seem pretty
awesome until we peer further into the depths of the cosmos where,
thanks to Hubbell Telescope in orbit around the earth, we can now see
what parts of the universe looked like many millions of years
because that's how long it took some of the images we see to
And what do we see? not millions, but billions of other galaxies of
various shapes and sizes, expanding away from a central point in space
where, scientists believe, everything got started about 18 billion
years ago. This is called the 'Big Bang' theory.
In our solar system (a collection of
planets held in orbit by the gravitational pull of our sun at the
centre) each planet orbits at a significantly different distance
from the sun, so the danger of them ever ever colliding is negligible.
believed, however, that near to the earth's current orbit, two planets
smaller than earth, made up of mainly iron and rock, shared similar
orbits and eventually did collide about 4.5 billion years ago. The
resulting debris eventually coalesced into one single planet - the EARTH - along with an
unusually large moon, the diameter of which is roughly 1/4 of the
earth's own diameter. It then took the next billion years
or so for it to cool whilst conditions settled sufficiently for an
atmosphere to form and for it to collect enough water from comets
attracted by its gravitational pull to make up the first lakes and
oceans conducive to the emergence of life.
The earth rotates once every 24 hours on an axis tilted at 23.5 degrees
from vertical to the plane of its own orbit around the sun. It takes
the moon 27.3 days to complete a single orbit around the earth, 1 year
for the earth to orbit the sun and 226 million years for our solar
system to complete one lap around the Milky Way's
|In an amusing, yet informative
sketch from Monty Python's 'The Meaning of Life', Eric Idle steps out
of a refrigerator into Mrs Bown's kitchen, to take
her on a tour of the
universe. Below is the transcript of his accompanying song.
Whenever life gets you down, Mrs.
Brown, and things seem hard or tough
And people are
stupid, obnoxious or daft and you feel that you've had quite enough!
remember that you're standing on a planet that's evolving, revolving at
nine hundred miles an hour.
It's orbiting at
ninety miles a second, so its reckoned, a sun that is the source of all
The sun and you
and me and all the stars that we can see, are moving at a million miles
In an outer spiral
arm at forty thousand miles an hour, of the galaxy we call the Milky
Our galaxy itself
contains a hundred billion stars, its a hundred thousand light years
side to side.
It bulges in the
middle sixteen thousand light years thick but out by us its just three
thousand light years wide.
We are thirty
thousand light years from galactic central point, we go round every two
hundred million years.
And our galaxy is
only one of millions of billions in this amazing and expanding universe.
itself keeps on expanding and expanding in all of the directions it can
As fast as it can
go, the speed of light you know, twelve million miles a minute and
thats the fastest speed there is,
So remember when
you're feeling very small and insecure, how amazingly unlikely is your
And pray that
there's inteligent life somewhere up in space, because there's b***** all down here on earth!
This is what a spiral galaxy looks
a few other galaxies in the distance
the moon's orbit
our place in the Milky Way
Observing the Milky Way