Feeling insignificant yet?

There a passage in Douglas Adams’ Hitchhiker’s Guide to the Galaxy (its supposedly in the introduction to the ACTUAL Hitchhikers Guide to the Galaxy) that’s describes the size of the universe …

Space, says the introduction to the guide, is big. Really big. You just won’t believe how hugely, mind bogglingly big it is. And so on.

Carl Sagan used to say the universe contained “billions and billions of stars” and also that if we are the only intelligent life in the universe, then what a ‘tremendous waste of space.” The following pictures are one of the best visual depictions of that I have ever seen, and it shows pretty clearly just how insignificant this little blue orb actually is.

These are the inner planets … the small rocky bodies cloe to the sun (well, excluding Pluto anyway) and Earth fares pretty well here. Our next door neighbour is almost our size, but we are the biggest of the bunch.

As we go farther out, we encounter the gas giants, huge balls of gas that are make our inner planets seem tiny in comparison. Notice that tiny Pluto is barely visible here, and even compared to the smallest of the gas giants, Neptune, Earth is pretty puny.

But of course, at the centre of our system is a burning ‘gas giant’ that completely dwarfs even the biggest planet, Jupiter. At this scale, Earth is barely visible and Pluto is little more than a darkened pixel on the image. The diameter comparison between the earth and the sun is 1-100, and volume-wise, approximately 1 million earths would fit inside the volume of the sun, according to NASA.

But the fact is, our sun is wholly unremarkable as stars go. Its certainly not the smallest we have observed, but by no means is it the biggest. Even in our ‘local neighbourhood’ as shown above, the sun is dwarfed by neighbouring stars. Arcturus is one of the brightest stars in the sky, and you can see that size is one reason why in comparison to our sun. Notice that Earth isn’t even visible at this scale, and Jupiter, the giant among planets in our system, is but a single pixel on this image.

But even Arcturus is dwarfed by the super-giants, massive red stars that would swallow huge chunk of our solar system. Antares and Betelgeuse, if they were placed at our Sun’s location, would easily envelope Mercury, Venus, Earth and Mars … Antares’ diameter is actually about 3/4 of the diameter of the ORBITAL diameter of Jupiter … that is, placed at the Sun’s position, the surface of Antares would extend almost as far out as the Jupiter. Notice that in planet size, Jupiter isn’t even visible at this scale, and our Sun is but a single pixel on the image.

So, if you aren’t feeling insignificant by now, I have a final image to post. It comes from a favorite T-shirt of mine (and I actually posted about this awhile back here) …

The arrow points (very roughly, ofc) to our Sun, all the stars shown in this post end up being within a tiny radius around that arrow. For those who like numbers, Arcturus was the Antares is the star above that’s farthest from our Sun, at about 600 light years, while the galactic disc is about 12000 light years across. And of course, it doesn’t even stop there … the Milky Way is but one galaxy among millions.

If you’ve always had trouble grasping the scales involved in astronomy, its no surprise really. As is apparent here, the scales involved are “Really big. You just won’t believe how hugely, mind bogglingly big” they are 🙂

Correction (25-Aug-06):

Rigel and Antares are actually a lot farther away than Arcturus … The mention of Arcturus above as the farthest away was a miss print for Antares originally (Antares is 600 ly away, Arcturus is 37 ly away, considerably closer), before I realized that Rigel is actually about 775 light years from us. For an accurate look at the distances between planets and stars (values that are several orders of magnitude larger than the sizes we are talking about here), check out my post And you though size mattered …

I apologize for the error …

Further Links:

• From unbelievably huge, to unimaginably tiny, see the whole world for the first time with “The Powers of 10“