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太阳有多大?

How Big Is The Sun?

太阳和月亮在地球上看起来差不多大
The Sun and the Moon are about the same size when you look at them in the sky, though that’s
虽然那归功于一个巧合 就是日地距离大约是月地距离的400倍
just thanks to the coincidence that the Sun is about 400 times farther away than the Moon
而且太阳的体积大约是月球的400倍 另一个有趣的巧合是
and also about 400 times bigger. Another fun coincidence is that the radius of the Sun
太阳半径大约是日月距离的两倍
is about twice the distance to the moon, so if you put the sun where the Earth is,
因此如果把太阳放在地球的位置 月球到太阳表面的距离也只是太阳半径的一半
the Moon would be just over halfway to the surface of the Sun.
而且 由于太阳太大 光线需要4.5秒多才能穿过它的表面
The Sun is also so big that it takes light over 4 and a half seconds to travel across
尽管我不知道这样描述更倾向于太阳很大或者光速
its face – though I don’t know whether that says more about how big the Sun is, or how
很慢 或者两者都有
slow light is, or both.
那么太阳系的其他星球都有多大呢 让我们用冥王星和卡戎星
What about the scale of other solar system objects? Well, here are Pluto and Charon compared
与地球和月球作对比
to the Earth and the Moon.
至于木星 一般来说 它的半径大约是地球的10倍
And Jupiter; which, as a rough rule of thumb, has about 10 times the radius of the earth
同时也就是太阳半径的十分之一
and one tenth the radius of the Sun.
土星比木星略小一点 但是土星的光环半径是土星半径的2倍
Saturn is slightly smaller than Jupiter, though its rings go out twice as far – still only
然而仍旧只是地月距离的三分之一
a third of the way to the Moon, though.
火星的卫星与火星的距离很近而且很小 它的大小也造成了另外一个巧合
Mars’ moons are very close and very small, which gives rise to another moon-sized coincidence:
从火星上看 火星和太阳大小相近 同时也会出现周期性日食
Phobos is almost the same size in the martian sky as the Sun, and can cause annular eclipses
就像出现月食一样
just like our Moon here on Earth.
如果天空中的两个星体看起来大小相近 就像月亮和太阳大小一样
If two objects have the same apparent size in the sky, like the Moon and the Sun, it
意味着它们的半径和它们到地球的距离之比是定值
It means that their radius divided by their distances is about the same value.This also implies
也就是说星体产生的潮汐力的大小相近 因为潮汐力大致和半径与距离之比的三次方成比例关系
that the strengths of the objects’ tidal forces, which are roughly proportional to
事实上 任意两个大小相近密度也相同的星体
the radius over the distance cubed, will also be about the same. In fact, ANY two objects
其潮汐力也
of roughly the same density that look about the same size in the sky will have tidal forces
大致相同
of similar strengths.
因此尽管在地球上看太阳和月亮的等大是个巧合
So while the apparent equal size of the moon and sun in our sky is a coincidence, the fact
但是事实上它们拥有相近的大小和大致相同的潮汐力
that they have similar apparent sizes and roughly similar effects on the tides is a
是几何和物理作用的结果
consequence – of geometry
and physics.

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https://www.youtube.com/watch?v=u70lZSMP9Bo

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