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There’s plenty of stuff in the universe that defies the human urge to categorize everything:
宇宙中有很多东西都无法满足人类对一切事物进行分类的欲望:
I mean, is Pluto a planet?
我是说，冥王星是行星吗?
Is this a new species or subspecies?
这是一个新物种还是亚种?
Man or woman?
男人或女人呢?
Green or blue or teal?
绿色、蓝色还是青色呢?
However, sometimes nature gives us a helping hand and provides a hard, physical line distinguishing two things,
然而，有时大自然会伸出援助之手，并提供一条确凿的的物理线来区分两种事物，
like the line between white dwarf stars, neutron stars, and black holes.
比如白矮星、中子星和黑洞之间的那条线。
These are the different possible kinds of corpses of dead stars,
这些是不同种类的恒星死亡的尸体，
and what distinguishes them is how they hold themselves up against the inexorable attraction of gravity.
它们的不同之处在于它们是如何抵御不可阻挡的地心引力的。
Let’s begin, though, with what makes something a star in the first place: fusion of hydrogen.
让我们从是什么让一个物质从一开始成为恒星开始:氢的聚变。
Below about 8% of the mass of the sun, a gas ball isn’t hot and high pressure enough for hydrogen to fuse
在太阳质量的8%以下，气体球的温度和压力不足以让氢聚变
and you get a failed star , essentially a really heavy version of Jupiter or Saturn.
就会有一个失败的恒星，本质上是木星或土星的重版本。
Above this dividing line are stars like red dwarfs, our sun, and so on ,
在这条分界线之上是像红矮星、太阳等恒星，
which use hydrogen fusion to keep themselves hot enough to stave off gravitational collapse.
它们利用氢聚变来保持足够的温度，以避免引力坍塌。
But eventually stars run out of fuel for nuclear fusion, and die.
但最终恒星会耗尽核聚变的燃料而死亡。
And when a star dies, it will turn into one of three very different and physically-distinct things.
当一颗恒星消亡时，它会变成三种物理上截然不同的东西之一。
If the star is small its core will turn into a white dwarf, which is an object about the size of the earth, almost as massive as the sun,
如果这颗恒星很小，它的核心就会变成一颗白矮星，这是一种和地球差不多大小的物体，几乎和太阳一样大，
and is held up against gravity not by heat but by electrons repelling each other due to the “Pauli exclusion principle”.
并不是通过热，而是由于“泡利不相容原理”电子之间的相互排斥来抵抗重力。
This effect is essentially a star-sized version of how electrons fill subsequently bigger orbitals around an atom,
这种效应本质上是一个恒星大小的版本，说明电子是如何填充原子周围更大的轨道的，
because of a fundamental law of the universe that no two electrons can share the exact same state.
因为宇宙的一个基本定律是没有两个电子可以共享完全相同的状态。
If the star is bigger, its core will be too heavy for this kind of electron repulsion to hold it up against gravity,
如果恒星更大，它的核心就会太重，这种电子斥力无法支撑它抵抗重力，
and instead it’ll collapse even more until it’s around 10 kilometers in size,
相反，它会进一步坍缩，直到大约10公里大，
all of its electrons and protons fuse together into neutrons,
所有的电子和质子都融合成中子，
and it’s held up instead by the nuclear repulsion between neutrons, as well as the neutron version of the pauli exclusion principle.
相反，它被中子之间的原子核斥力所支撑，以及泡利不相容原理的中子版本。
Aka, a neutron star.
也就是中子星。
If the dying star is yet bigger still (or if two neutron stars collide and merge),
如果垂死的恒星更大(或者两颗中子星相撞并合并)，
its core will be too heavy for either the strong nuclear force or pauli exclusion principle to hold it up against gravity, and it will collapse until it’s held up by –
它的核心太重了，无论是强核力还是泡利不相容原理都无法支撑它抵抗重力，它会塌缩，直到被支撑住，
well, as far as we know there’s not anything left to hold up stuff this dense , and it’ll collapse into a black hole.
据我们所知，没有任何东西能支撑如此致密的物质，它会塌缩成黑洞。
So when a star dies, what it turns into depends on its mass,
所以当一颗恒星死亡时，它会变成什么，取决于它的质量，
and what distinguishes these star corpses from each other is what they’re made of and how they hold themselves up against gravity (or don’t).
而这些恒星残骸之间的区别在于它们是由什么组成的，以及它们如何抵御(或不)引力。
But enough about space objects that have nice, clean, easy definitions.
有漂亮、干净、简单定义的太空物体已经足够了。
There's also a lot of stuff out there that doesn't fit nicely into boxes.
但还有很多东西不能很好地放进这个范围里。
Like moons.
像月球。
We supposedly have a good definition for what a moon is
我们应该对月球有一个很好的定义
but our solar system is full of objects that fall into a weird grey area between moon and not moon.
但我们的太阳系充满了落入奇怪的月球和非月球之间灰色地带的物体。
Come over to MinuteEarth to find out why our definition of "moon" might be broken!
来一分钟地球，了解为什么我们对“月球”的定义可能会被打破!
