Friday 2nd December

The Universe is quite large.  In fact it is so large that we simply cannot comprehend how vast it is.  We measure most of it in light years; that is how many years that light, which travels at 186,000 miles a second, takes to reach us.  And what we are seeing is light from years ago; the very stars we can see may have already burnt out long ago, and certainly will be by the time we ever travel to them.  And although the Universe is so vast it is almost entirely made of nothing.  There are huge spaces between planets and stars; our own planet is 93 million miles away from the Sun, which can feel so warm on our skins even when it is low in the sky.  And out there in that vast nothingness there is no friction to slow things down, once on a trajectory planets, comets and stars just keep going until they come within the gravitational pull of some other star or planet.  And then size becomes important, or rather mass does.  The heavier a planetary body is the greater the gravitational pull.  And the whole thing is hanging together on invisible threads of gravity, just as the Earth is strung along lines of forward motion from wherever we came from and pulled by the Sun’s gravity into an orbit we can never escape unless something bigger comes along and drags us away.  The whole of our Milky Way is like a cats-cradle with Stars and planets whirring around but from afar appearing static, all held in motion by Gravity.  We are spinning madly around the Sun and yet feel no motion at all, held still by that very same force of Gravity.  And our moon cannot escape us either, held in place by our own gravitational pull.  And even the satellites we send up and all the bits of debris we are littering space with are orbiting just far enough out to be held in check by gravity.

We are still exploring our own incredible yet tiny Solar System where the planets are millions of miles apart and yet all part of the same gravitational pull exerted by the sun.  And elsewhere in the vastness of the Universe are billions of Solar Systems all equally oblivious of each other but trapped and strapped to each other by their relative size and gravity.