The reason we can be reasonably confident that such an event won't happen in our corner of the galaxy¹, Thorstensen said, 索尔斯坦森说，有理由相信，这种事情在星系的我们这个角落里不会发生，

is that it takes a particular kind of star to make a supernova in the first place. 这是因为，首先，形成一颗超新星要有一种特别的恒星。

A candidate star must be ten to twenty times as massive as our own Sun 恒星非得要有我们的太阳10-20倍那么大小才有资格，

and "we don't have anything of the requisite² size that's that close. 而"我们附近没有任何符合这个条件的星球"。

The universe is a mercifully big place." 非常运气，宇宙是个大地方。

The nearest likely candidate he added, is Betelgeuse, 他接着说，离我们最近的、很可能有资格的，是猎户座；

whose various sputterings have for years suggested that something interestingly unstable³ is going on there. 多年来，它一直在喷出各种东西，表明那里不大稳定，引起了大家的注意。

But Betelgeuse is fifty thousand light-years away. 但是，猎户座离我们有5万光年之远。

Only half a dozen times in recorded history have supernovae been close enough to be visible to the naked eye. 在有记载的历史上，只有五六次超新星是近到肉眼看得见的。

One was a blast in 1054 that created the Crab⁴ Nebula⁵. 一次是1054年的爆炸，形成了蟹状星云。

Another, in 1604, made a star bright enough to be seen during the day for over three weeks. 另一次是在1604年，创造了一颗亮得在3个多星期里连在白天都看得见的恒星。

The most recent was in 1987, when a supernova flared⁶ in a zone of the cosmos⁷ known as the Large Magellanic Cloud, 最近一次是在1987年，有一颗超新星在宇宙一个名叫大麦哲伦云的区域闪了一下，

but that was only barely visible and only in the southern hemisphere 然而仅仅勉强看得见，而且仅仅在南半球看得见

and it was a comfortably safe 169,000 light-years away. 它在16.9万光年以外，对我们毫无危险。