Friday, September 4, 2009

Mote of Dust in a Sunbeam

"That's here. That's home. That's us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives... lived there--on a mote of dust suspended in a sunbeam." ~ Carl Sagan

Carl Sagan said this when observing a photo taken by Voyager in 1990 as it exited our solar system, nearly four billion miles away. "Mote of dust" however, makes the earth sound far too large in the grand scheme of the universe. Shall we take a look?

This is Earth as seen from the moon, taken by the Apollo astronauts. Looks fairly large still:
This is Earth compared to our Sun, a small and fairly insignificant star when compared to most:
This is the image that Carl Sagan was commenting on when he said the above. This is Earth from about 4 billion miles away, a tiny spec of light in a sunbeam (it is the pale blue spec between the two lines):
If that does not make it look small enough, consider this size comparison. The Milky Way contains about 100 billion stars (of which our Sun is only one, a small one) and they are nothing but specs of light that make up the galaxy. Below is an image of the Pinwheel Galaxy, a galaxy not too dissimilar from our own. I have marked with a red dot where our solar system would be if this was our galaxy. The dot is not to scale, of course, if it were you would not be able to see it:
Finally, in 2004 the Hubble Space telescope stared for 11 days at a rather boring patch of sky, collecting light. The image it recorded, however, is anything but boring. It recorded what is known as the Ultra Deep Field image. It is the farthest ever seen into the universe. In this image there are more than 10,000 galaxies, some larger than ours and some smaller. Each dot in the image is a galaxy, each galaxy contains billions of stars:
See what I mean when I say that "mote of dust" makes Earth sound too large in the grand scheme of the universe? The universe's radius is 78 billion light-years (0.2 bailout-light-years). That is 4.58522986×1023 miles. Makes me feel kind of small when I think about it. Fortunately, God holds all this in His hand and He likes me a lot.

By His Grace,
Taylor

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