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Oct 6, 2010

It's a long way to the next useful planet

Today, a slight departure from the usual topic of this blog.

Recently, there has been a lot of excitement about the discovery of Gliese 581g, a planet orbiting a star that is around 20 light years away from here in the constellation of Libra. What makes this extra-solar planet so interesting? It is believed to be rather Earth like in mass and one of the first so-called "Goldilocks" planets: Located in the habitable zone around its star, not too far and cold, not too close and hot, but just right for life to possibly exist there.

On a cosmic scale, 20 light years is pretty much nothing. For us humans, though, it's still very, very far away. For comparison: An Astronomical Unit (AU) is the average distance of Earth from the Sun, which is about 149.6 million kilometers. Light actually needs over 8 minutes to travel this distance! Now assume that our solar system has a diameter of roughly 80 AU or almost 12 billion (!) km, which is more or less the diameter of Pluto's orbit. A somewhat old-fashioned way to measure it I will admit, but old habits die hard. The Voyager spacecrafts, launched more than 30 years ago have traveled just over this distance now. Our solar system may be vast, but light can still cross it in just 11 hours.

But Gliese 581g is over 20 lightyears away.

Now how can we put this into perspective? How can we show how incredibly far away Gliese 581g is, compared to anything we can even remotely begin to comprehend? Well, I tried. Below is an extremely simple 'infographic'.

At the top of the image you see a single-pixel dot in the middle of a square. That dot is the diameter of the solar system! Not the square, just the dot in its center. A single pixel representing all 80 AU, or 11 light hours; a distance it takes us around 30 years to travel with our current technology.

Then start to scroll down. And scroll... and scroll...

And here we are! 20 light years away from our solar system, away from our home. Hopefully, we remembered to turn the ship around at some point in order to slow down for our arrival.

To recap, on this scale the diameter of the entire solar system is just 1 pixel! The image above is more than 15,000 pixels high. This means that the distance to Gliese 581g is 15,000 times more than the diameter of our solar system! The distance between Sun and Earth is 1/80th of a pixel. The diameter of Earth? Around 1/1,000,000 of a pixel.

We have a long way to go.

I would be happy if you would follow me on Twitter. You might as well, after having traveled 20 light years...

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