Babe Among The Stars

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Galaxy Babe's column banner, showing a full moon and some little folk looking up at the sky

Mortal as I am, I know that I am born for a day. But when I follow at my pleasure the serried multitude of the stars in their circular course, my feet no longer touch the earth - Ptolemy

The End of the World

In honour of hootoo's tenth birthday, I'll list the top ten causes some astronomers think may bring about the end of the world:

  1. NEOs: the Earth is like a giant target hurtling through space, being bombarded by random space bodies which may or may not burn up in our atmosphere. One of these killed off the dinosaurs, giving mammals (us) a chance to go to the top of the food chain. When the next space impact occurs the devastation will be catastrophic: if the initial blast doesn't wipe us all out then we'd probably freeze in a nuclear winter or starve to death.

  2. Our Sun is an insignificant yellow dwarf star. Eventually though, it will run out of nuclear fuel and expand into a red giant star. This will overwhelm the Earth with heat, the oceans will boil and evaporate, we'd no longer be in the 'habitable zone'. No need to panic though, the Sun has enough hydrogen to burn for another few billion years.

  3. A pulsar is a pulsating neutron star, like the one which powers the Crab Nebula. They emit a blast of radiation so powerful that if one were to hit the Earth it would be toast.

  4. Gamma Ray Bursts (GRBs) thankfully have only occurred outside our galaxy, or we wouldn't be here now. Effectively this is the collapse of a giant star which may lead to the birth of a black hole.

  5. A black hole lurks at the centre of our galaxy. Once in its clutches even light can't escape, so we'd have no chance. Luckily we orbit the Sun which doesn't visit the galactic centre on its travels. However, the Andromeda Galaxy, which also boasts a black hole, is headed in our direction on a collision course and scientists don't know what will happen to the two galaxies post-collision. They may merge, they may tear each other apart, but individual stars should be OK. We just might be lucky, or we might end up with a black hole for a neighbour and we'd be spaghettified.

  6. A star that is large enough can go supernova at the end of its life. Worryingly, there are stars in our own galaxy which fit the bill, and one is close enough (420 light years) to have a detrimental effect, should it happen sooner than later. Betelgeuse is so famous it has its own Edited Guide Entry. Another massive star, the hypergiant Rho Cassiopeiae, 40× the mass of our Sun, will likely be the first one to blow. Thankfully it is over 8,000 light years distance so we'll be in the audience when that happens, not part of the act.

  7. The Sun could belch. This doesn't sound like the end of life as we know it, but one spectacular eruption of stellar material in our direction would be a fatal whiplash. Aurorae are quite pretty to look at but these are actually solar winds interacting with the Earth's magnetic field; our atmosphere deflects the harmful radiation. High solar activity can take out orbiting satellites beyond this protection, and large eruptions, capable of destroying the ozone layer, are impossible to predict. Well, we'd get about eight minutes' warning.

  8. Mankind could destroy itself, whether by dabbling with nature, creating more destructive bombs or – in the name of science – experimenting with things like the Large Hadron Collider. It makes little difference, our world has been continuing its merry way revolving around its star for billions of years and hopefully it will continue to do so long after the demise of the human race.

  9. The Sun powers everything on the Earth. Without it there'd be no plants, animals, us. We take it for granted that it's always going to rise the next morning bringing once again its life-giving energy. We assume its temperature won't fluctuate to detrimental extremes at our peril. Sunspot activity at the moment is at its lowest for about a hundred years. Solar experts don't know what's going on with the Sun, just that there are currently no sunspots and very few solar flares. According to the Sun's usual 11-year activity cycle, it was supposed to be hotting up this year. The figures are quite alarming: a 50-year low in solar wind pressure, a 55-year low in radio emissions, and a 100-year low in sunspot activity.

  10. Extra-terrestrial aliens. Some people think they are already here but there's no physical evidence, or anything left to analyse from the famous UFO crash over 60 years ago at Roswell. We've been treated to just about every ET-scenario courtesy of the science-fiction genre, from friendly hitchhikers to intergalactic pirates after our planet's wondrous resources, including us on the menu. Looking at the real possibilities though, just suppose a spaceship did land on the White House lawn in full glare of the world's media. Assuming they weren't blasted into oblivion by the new Prez's personal security detail we as a race would probably offer them our hand in friendship. Then what? Discussions around a large oval table? How would we understand them unless they've thoughtfully learned English in preparation? What if they were so vastly different from us that it threw the whole God-fearing population into a panic and caused worldwide pandemonium, leading to riots and looting, culminating in total breakdown of society. What we'd want to know is, what do they want? Worst-case scenario (for us) would be – our planet, because their own had been, or was in the process of being, destroyed or becoming uninhabitable. We'd be in the way, unless they were ocean-dwellers who might be able to populate our seas with no detrimental effect to us. If they were more highly evolved than us, would they want to share their bounty? Or would they look upon us as ants to be trodden underfoot? Best-case scenario – they come in peace to warn us about what we as a race are doing to our beautiful planet, we shouldn't be so ungrateful and need to change our ways. Hopefully they'd be as innocuous as intergalactic Jehovah's Witnesses...

  • Chat about your celestial observances at the H2G2 Astronomy Society. Comment on anything in this edition of Babe Among the Stars by starting a new conversation below.

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