DECEMBER 3rd [Science Comedy Advent Calendar]

December 3rd: Neutron stars

For various unspecified reasons, big shiny baubles have become quite a prominent feature of Christmas. Whether the flawless sphere is symbolic of the crystal spheres that surrounded the earth in the ancient geocentricmodel of astronomy (which was probably in vogue at the time of the birth of Christ), or the most cost effective shape for the mass production of pointless decorations, they’re everywhere in December. I don’t really know, and I don’t care enough to find out.

But speaking of celestial spheres, the universe has its own shiny baubles. What would make a better shiny decorative bauble than a typical neutron star?

Almost anything would make a better bauble, actually. Tying a mangled turkey bone to your tree would be a better idea. Neutron stars, although technically big, shiny baubles in the strictest sense of the term, are typically around 12km across and mass more than half a million Earths. A teaspoon full of neutron star matter would weigh the same as 900 great pyramids. Or 1200 average ones.

Now, I guess it’s feasible that they can make teaspoons that can endure that sort of treatment, but I doubt any fir tree in existence could withstand having a neutron star hung from it, even if it is one of those fancy plastic ones (the tree, not the star).

Obviously, bringing a neutron star within the boundaries of the solar system would likely play merry hell with the orbits of the planets, so bringing one to within 2 metres of the Earth’s surface to attach to a plant would undoubtedly end all life on and probably destroy the physical integrity of the planet itself. And that would ruin Christmas.

You could argue that all stars are big shiny spheres, and in a very loose sense you would be right. I singled out neutron stars as they resemble Christmas baubles the most due to the fact that most neutron stars seem to have a solid ‘shell’. Granted, they do have an atmosphere that is about 1m thick at most. For contrast, if the earth had an atmosphere that was 1m deep, you would be in the vacuum of space if you stood up and your head would probably explode. But if you were on a neutron star, you couldn't stand up at all, so that's not a worry. Although being that close to it would have reduced you to an atom-thin spread anyway, so no need to worry either way.

 But a typical neutron star, thanks to the extreme gravity, has a very smooth, hard surface. They also emit visible light at pretty much all wavelengths, making them especially shiny and more ‘bauble-esque’ than most stars with their thousand-kilometre deep chromospheres and turbulent ‘surfaces’ of plasma.

Neutron stars are the remnants of massive stars that have since gone supernova, and the extreme gravity allows the star to overcome electron degeneracy pressure, a property that prevents too much mass from condensing into one place.  By violating the rules of normal matter, neutron stars matter is possibly the densest substance in the universe, relegating to second place the previous title holder, Christmas Pudding.

So because of these properties (not including countless others), Neutron stars are quite Christmassy. But that’s just in isolation. What if two of them meet and, more importantly, collide? They’re essentially big balls, right? And balls often come in pairs, don’t they.

It has been suggested that, if conditions are right, two neutron stars can end up orbiting each other, getting closer and closer until eventually they collide and produce a horrific onslaught of unimaginable carnage. Neutron star collisions are one suggested cause of gamma-ray bursters, the most energetic events in the universe, unleashing the same energy in seconds that the sun releases in its 10 billion year lifetime. If such a thing occurred even within our galaxy, it would release a wave of radiation that could decimate/annihilate life on Earth.

A long, slow build up which involves a sense of coming together, a brief spectacular light display, followed by a period of carnage and devastation; What more fitting metaphor for the turning on of the city centre Christmas lights could you ask for?

Twitter: @garwboy. for regular updates