For example, some experts believe that our Sun has a very dense, dim twin star which is too far away to observe directly. This sleeping giant, dubbed the “Death Star”, could distort the paths of orbiting chunks of icy rock and hurl them towards the rest of the Solar System.

Is this what happened 252 million years ago? Or is there instead, perhaps, a distant, ninth planet in our Solar System which pulls in passing comets and sends them hurtling our way?

If that isn’t enough to put you off your breakfast, then consider what’s happening to our friend, the Sun. The star that has given us the warmth to sustain life is gradually turning into a deadly foe. Like all stars, it is slowing dying, burning through its energy supplies. As it does so, it expands, and in about 2 billion years it will have grown so much that the heat will make life on planet Earth unbearable.

While all this sounds a little macabre, take comfort from the fact that the chance of being hit by a giant interstellar projectile is incredibly slim, and that 2 billion years is a very long time.

And there’s another thing: if the dinosaurs had not snuffed it when they did, it’s extremely unlikely that human beings would have had the chance to evolve at all.

词汇表

little green men （比喻）外星人

meteorite 陨星、陨石

cosmic ray 宇宙射线

good old （赞美语气）老牌的、靠谱的

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