Peering into the depths of space

Chandra Deep Field South (source: ESO)

If you take an interest in science you may have seen reports of the first visible light images of planets outside our solar system. With the Gemini North telescope on Hawaii’s Mauna Kea, three planets were found orbiting HR 8799, a young star some 130 light years away in the constellation Pegasus. And with the Hubble telescope astronomers have discovered a Jupiter-sized planet in a dusty disk surrounding Fomalhaut, the brightest star in Pisces.

The detailed results published in the journal Science (see here and here) are hugely important. Being able to image planets directly will allow us to study their composition and atmosphere, and in the process learn more about the formation of our own solar system. But so far we can only just resolve planets the size of Jupiter at massive distances from their parent stars. Small, rocky bodies that could sustain life as we know it orbit much closer, and Earth-like planets cannot be resolved with current terrestrial telescopes.

Exciting though these exo-planet images are, for astronomical wow-factor it would be dificult to beat the picture accompanying this post, which shows a pool of galaxies of many different shapes and colours in a region of space known as the Chandra Deep Field South. The image covers an area of around 14 by 22 arc minutes, and is the result of 40 hours of observations with the Very Large Telescope in Chile’s Atacama Desert. It shows galaxies a billion times fainter than can be seen with the naked eye.

To put the size of this small region of sky into perspective, the sun and moon are both around 30 arc minutes across. Picture these objects high in the sky and not near the horizon, where an optical illusion makes them look much bigger than they really are.

Click on the image above to download a full-resolution JPEG. Be warned, though, that this is over 31 megabytes in size, and could therefore take a while, depending on your network connection. Alternatively, ESO has helpfully provided a zoomable image.

If you spend all your time in urban areas, you may never have experienced the wonders of the night sky, obscured as they are by all the artificial light we throw out. But in the blackness of a country night, far away from towns and cities, you can resolve star clusters and even a few of the brighter galaxies outside the Milky Way. Now just imagine diving into a tiny portion of the void between the stars you can see with your own eyes. There you have the Chandra Deep Field South, and many more like it.