Monday, June 13, 2016

93 BILLION LIGHT YEARS

The Andromeda Galaxy. The closest galaxy to us, it is only 2.54 million light years away.

Article in today’s BBC News tells us that astronomers have now calculated the size of the universe. The long but interesting article relates how they came to their current conclusion that the diameter of the universe is 93 billion light years. (Not miles: light years. A light year is the distance light travels in a year, or about 6 trillion miles. Do the math?) Those of us who remember a bit of high school geometry will realize that nothing was said about the circumference or the area of the universe. 93 billion is a big enough number, especially if it is multiplied by 6 trillion. That comes to a number in the sextillions. When they use the word 'astronomical' they really mean it. Only astronomers can think in that kind of numbers.

Just think on this: our own Milky Way galaxy, which over time has been estimated at various sizes, originally with the Earth believed to be at its center. It is now known to be about 100,000 light years across – give or take a few light years.

The Fornax Cluster of galaxies. With some stars from our own galaxy in the foreground, each of those yellow dots is a galaxy in itself.  This is about 62 million light years away.

For those of us who regularly deal in miles or kilometers, or even the length of a city block or a football field, light years are almost mythical. To bring it down to earthly size, I suppose the Earth is not the seed in the watermelon or the flea on the dog, it’s probably not even like the proverbial grain of sand on a coral beach. No, I’d guess we’re more like the atom of carbon in that grain of sand.


Makes you start thinking about the bigger picture - about all the now seemingly insignificant problems besetting our planet, and the relatively insignificant beliefs we hold. Start thinking about all the beings who most assuredly populate the countless worlds between us and the edge of the known, ever expanding universe. How do they live, what are their problems, who are their gods? Thoughts like this shouldn’t keep you up at night. Maybe, if you pursue them in depth, they'll put you to sleep.

Our own Milky Way galaxy. We see it from the inside.


Photos from Astronomy Picture of the Day - apod.nasa.gov





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