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19 January 2011

Bad Astronomy: How deep the Universe

So Dr. Plait had a great post about perspective that I just had to share.  I swear that I heard Douglas Adams reading from The Hitchhikers Guide to the Galaxy when I read this.  You know, like:
“Space is big. You just won’t believe how vastly, hugely, mind- bogglingly big it is. I mean, you may think it’s a long way down the road to the drug store, but that’s just peanuts to space.” – Douglas Adams.
Of course, looking at things like this can certainly make you feel small and insignificant if you aren't prepared for the grandeur of the universe.  On the other hand, this is something that should be incredibly awe inspiring.  As a matter of fact, it reminds me of another quote, this time by Carl Sagan:
In some respects, science has far surpassed religion in delivering awe. How is it that hardly any major religion has looked at science and concluded, "This is better than we thought! The Universe is much bigger than our prophets said, grander, more subtle, more elegant. God must be even greater than we dreamed"? Instead they say, "No, no, no! My god is a little god, and I want him to stay that way." A religion old or new, that stressed the magnificence of the universe as revealed by modern science, might be able to draw forth reserves of reverence and awe hardly tapped by the conventional faiths. - Carl Sagan
Anyway, on to Dr,. Plait's excellent post and beautiful pictures.  And please, click through to his post, I cut off before some really mind blowing pictures that were taken out of the main one.  You'll see what I mean!

How deep the Universe

The Universe is a big place.

I mean, really big. Big everything for anything. Literally, big enough for everything. Everything you see, everywhere you go, it’s all inside. And there’s room for all of it, with space to spare. I get used to it sometimes, and then, suddenly, I’m thrown into a state where I’m forced to remember just how much of the Universe there is.

Let me show you something:

[Click to galactinate, and while it may take a little while to download the entire 3500 x 2000 pixel image, it will definitely be worth your time.]

This is the nearby spiral galaxy NGC 1345 as seen by Hubble. Lovely, isn’t it? You wouldn’t even think it’s a spiral at first; the arms are so faint compared to the sprawling core and inner regions. But it so happens the galaxy is close to our own, making fainter parts easier to observe.

Now there you go. Did you see that? What I said? "The nearby spiral…". "The galaxy is close to our own…". But it isn’t.

Look. Let your eyes move to the top of the galaxy, just to the right of center. See that bright star? You can tell it’s a star because it has those spikes going through it, an artifact of how point sources are seen by some of the Hubble cameras. Given how bright it is, that star is almost certainly in our own galaxy, and not some luminous giant in NGC 1345; it’s just coincidentally superposed on the more distant galaxy. That means it’s no more than a few thousand light years away, and given its deep red color, that means it’s most likely a very cool and faint red dwarf, and therefore in all likelihood much closer even than that.

But even if it’s only a thousand light years away, that’s 10 quadrillion kilometers! That distance is impossible to imagine: it’s more than 60 million times farther away than the Sun… and the Sun is hardly close. If you could fly an airplane to the Sun, it would take 20 years. Twenty years! And that star is millions of times farther away.

… and that star is the closest thing in that picture. I said NGC 1345 is nearby, and on a cosmic scale it is; it’s part of a small cluster of galaxies a mere 85 million light years away: 850 quintillion kilometers. That’s 850,000,000,000,000,000,000 kilometers.

"Nearby."


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