“Just So Science” – The Clouds that Weren’t

By Elf Eldridge 11/05/2011 1


What’s the best thing about living in the Southern Hemisphere? Winter! Sure, the above image is taken from an observatory in Chile, but in NZ we get treated to a similar view of the centre of our galaxy, the Milky Way, and they just get better and better as we move further and further into winter. To really appreciate it you need to position yourself somewhere without too much light pollution (Stonehenge Aotearoa in the Wairarapa is my pick!) but even from Wellington on a good night we can get some pretty spectacular views.

Small and Large Magellanic Clouds
Small and Large Magellanic Clouds

To see this in our skies look directly south-east an hour or so after dark and what you will see is the above image rotated approximately 90 degrees clockwise. The widest section of the bright ‘haze’ of starlight will sit almost directly on the horizon (near the constellation of Scorpius), and will thin out higher up in the sky, almost completely disappearing by the time it reaches the Southern Cross. If you’re luck enough to have a REALLY clear night you will be able to easily make out the large and small Clouds of Magellan (the ‘blobs’ of light on the left of the above image) – they do just look like clouds and will appear high up in the southern sky. Closer inspection reveals them to be two ‘dwarf’ galaxies (i.e. only a few billion stars-a-piece) orbiting our own.

The smaller of the two is ~200,000 light years away (roughly twice the diameter of our own galaxy), and near it is a huge cluster of bright stars known as 47 Tucanae visible in the image to the right. This actually has nothing to do with the Small Magellanic Cloud (SMC), it’s a globular cluster that is part of our galaxy, but just appears adjacent to the SMC as our ‘binocular’ depth perception fails miserably at cosmic lengths!

The larger of the two ‘clouds’ is simply one of the most spectacular things that can be seen in the night sky, and is only visible to observers in the southern hemisphere. It’s a little closer and bigger than the Small Cloud, a paltry 160,000 light years distant. It’s home to the ‘Tarantula Nebula‘ – an ENORMOUS cloud of Hydrogen gas (the red blob in the LMC closeup below) lit up by light from the vast number of stars that are forming near to its centre.

Large Magellanic Cloud with Tarantula Nebula to the left
Large Magellanic Cloud with Tarantula Nebula to the left

The predominant view of the fate of these galaxies is that their orbits will gradually decay until they crash into our own galaxy in a few billion years time – although what effect this will have on the Milky Way is still under contention – suffice to say that it’s unlikely to be hugely beneficial to humans if we’re still around then!

Dont worry if you cant find these yet – it’s just a very brief overview of what’s ‘visible’ if you know how and where to look! I’ll most more detailed locations, images and maps as soon as I get a chance!


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