So you take the huge Hubble telescope that orbits the earth and you focus it on a spot near the Big Dipper, a spot about the area of the width of a dime seen at 75 feet, and you shoot a picture. Not much to look at, I think you'll agree, but I believe I can change your mind about that. All but a handful of the blobs and specks of light in the photo are galaxies; immense systems of stars, gas and dust trillions of miles across. Our own sun lives in one such galaxy, a collection of over 200 billion stars.
There are about 1,500 galaxies in the photo, the dimmest ones more than 4 billion times fainter than the human eye can perceive and the light from these began it's journey to the Hubble telescope over 12 billion years ago. The larger blobs are relatively nearby galaxies; their light left them a paltry billion years ago. Doing some math, this little photo must then encompass an area it would take light 11 billion years to cross. I pretty big back yard, you have to admit.
Now, if we were to survey the entire sky in units the size of this photo, the total exposure time would be over one million years. And, if astronomers are correct and the distribution of galaxies is pretty much even across the sky, then we are talking about an incomprehensibly huge number of galaxies. And, if each galaxy contains at least 100 billion stars, then the number of stars is beyond imagination, billions of times greater than the number of grains of sand on the entire earth.
Our cosmos is not just big. It is incomprehensibly vast, measured in numbers we have never encountered and the size of which is so great as to be meaningless. So; of all imaginable realities, why this particular one? Is it no wonder, without the telescope, that the ancients got it all wrong.
Thursday, 12 April 2012
Tuesday, 10 April 2012
Where the wild things are
Welcome to my blog on things wild and wonderful, my grab bag of astonishing facts and figures that constantly renew my sense of amazement and wonder and routinely bring me to the threshold of what I regard as the unfathomable mystery of existence - why there should be anything at all and WHY THAT ANYTHING SHOULD BE PRECISELY THIS. Expect almost anything . I am an equal opportunity collector of remarkable stuff that should strike a receptive cord in the mind of somebody out there.
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