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The Sun and the Moon are about the same size when you look at them in the sky,
当你仰望天空中的太阳和月亮时，它们的大小是一样的，
though that's just thanks to the coincidence that the Sun is about 400 times farther away than the Moon and also about 400 times bigger.
虽然这只是由于巧合，太阳比月球远400倍，也比它大400倍。
Another fun coincidence is that the radius of the Sun is about twice the distance to the moon,
另一个有趣的巧合是，太阳的半径大约是月球的两倍，
so if you put the sun where the Earth is, the Moon would be just over halfway to the surface of the Sun.
所以如果你把太阳放在地球所在的地方，月球就刚好是太阳表面的一半以上。
The Sun is also so big that it takes light over 4 and a half seconds to travel across its face –
太阳也是非常的大，以至于光穿过它的表面需要4秒半的时间——
though I don't know whether that says more about how big the Sun is, or how slow light is, or both.
虽然我不知道这是否更多地说明了太阳有多大，还是光有多慢，还是两者兼而有之。
What about the scale of other solar system objects? Well, here are Pluto and Charon compared to the Earth and the Moon.
那么其他太阳系天体的大小呢？对比一下冥王星和冥卫与地球和月球。
And Jupiter; which, as a rough rule of thumb, has about 10 times the radius of the earth and one tenth the radius of the Sun.
木星，根据粗略的经验，它的半径是地球的10倍，太阳的十分之一。
Saturn is slightly smaller than Jupiter, though its rings go out twice as far – still only a third of the way to the Moon, though.
土星比木星略小一些，尽管它的光环比木星大两倍——尽管它离月球的距离仍然只有木星的三分之一。
Mars' moons are very close and very small, which gives rise to another moon-sized coincidence:
火星的卫星非常近，非常小，这导致了另一个月球大小的巧合：
Phobos is almost the same size in the martian sky as the Sun, and can cause annular eclipses just like our Moon here on Earth.
火卫一在火星的天空中几乎和太阳一样大，就像我们地球上的月亮一样，它能造成日环食。
If two objects have the same apparent size in the sky, like the Moon and the Sun,
如果在天空中两个物体有相同的大小，比如月亮和太阳，
it means that their radii divided by their distances are about the same value.
这意味着它们的半径除以它们距离是等值的。
This also implies that the strengths of the objects' tidal forces,
这也意味着物体的潮汐力的强度，
which are roughly proportional to the radius over the distance cubed, will also be about the same.
（大致与距离的三次方的半径成比例）也将是相同的。
In fact, ANY two objects of roughly the same density that look about the same size in the sky will have tidal forces of similar strengths.
事实上，任何两个密度差不多的物体，在天空中看起来大小差不多，都会有相似强度的潮汐力。
So while the apparent equal size of the moon and sun in our sky is a coincidence,
所以，虽然月球和太阳在我们的天空中看起来大小相等是一个巧合，
the fact that they have similar apparent sizes AND roughly similar effects on the tides is a consequence - of geometry and physics.
事实上，它们有着相似的表面尺寸和大致相似的潮汐效应，这是几何学和物理学的结果。
