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Size of the Universe part 2

February 16, 2012

It would be appropriate to begin with a quote from Douglas Adams’ book ‘Hitchhiker’s guide to the galaxy’:

“Space,” it says, “is big. Really big. You just won’t believe how vastly hugely mindboggingly big it is. I mean you may think it’s a long way down the road to the chemist, but that’s just peanuts to space.

I wanted to revisit an old post of mine titled ‘Size of our Universe’ . Needing a dose of ‘awe’, space always delivers. Now if someone could just bottle the stuff and sell it for cheap on-the-go.

My first selection is an image popularised by Carl Sagan who later titled one of his books with the same name. The ‘Pale Blue Dot’ is a photograph that contains just that, a small speck visible in a band of light radiating from our Sun; the dot is Earth. The image is the furthest ever point from which our planet has been photographed and will remain that way for a while until Richard Branson decides on the next generation of space flights ferrying cashed-up Japanese tourists with their handhelds.

Pale Blue Dot - Earth

At a distance of 6 billion kilometres, the celestial ball we all occupy resembles insignificant dust. If Douglas’s mind decided not to destroy earth to facilitate the  intergalactic highway, Earth’s plight would still be that of road-kill. I would agree with Sagan, viewing an image such as this can be “humbling” and a “character building experience”.

Here is a video of Sagan narrating a small passage from the first chapter of his book ‘Pale Blue Dot’.


The second image is called ‘Hubble Ultra Deep Field’. At first glance it may resemble a black napkin that withstood projectile food splatter from a large sneeze, but be assured it’s much more than that. The sudden comprehension of the content and the magnitude displayed within it may actually cause you to spray your food/drink in astonishment.

Hubble Ultra Deep Field

Each of those ‘food stains’ is in fact a galaxy or a cluster of galaxies. The image contains around 10,000 objects and is the deepest image of the universe ever taken. Our own loyal galaxy, the Milky Way contains anywhere between 200-400 billion stars, nothing to brag about at the intergalactic pageant, an average amount in fact. Taking that figure & multiplying by 10000, your sense of comprehension should buckle at the knees with the sheer astronomical volume of matter. Let us not forget the many more shrouded planets that escape our technological eye.

The image took 800 exposures to compile. All up the process lasted a period of four months with exposure lengths totalling up to a million seconds. But what fraction of the whole sky around us does this image cover? Here is where you begin to choke on your food after inhaling with bewilderment. A mere sliver, from the total our eyes could turn to. The whole sky contains 12.7 million times more area than seen in the ‘Hubble Ultra Deep Field’ photograph. It would take roughly 1 million years of uninterrupted observing to map the rest. The universe is vast indeed.

The final link is an updated version of an interactive flash tool that allows you to scroll through orders of magnitude in distance. Spanning from the theorised Plank length to the outer bounds of the visible universe the link provides objects in all scales and sizes.

Some references

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