为什么地球会不会“总是白天”如果“每日周期的阳光”是全面吗?- 江南体育网页版- - - - -地球科学堆江南电子竞技平台栈交换 最近30从www.hoelymoley.com 2023 - 07 - 10 - t05:59:35z //www.hoelymoley.com/feeds/question/6967 https://creativecommons.org/licenses/by-sa/4.0/rdf //www.hoelymoley.com/q/6967 6 为什么地球会不会“总是白天”如果“每日周期的阳光”是全面吗? dat tutbrus //www.hoelymoley.com/users/4861 2015 - 11 - 22 - t13:14:08z 2019 - 11 - 01 - t15:26:55z

The question is clear enough in my opinion but, I've found out that if you redraw this picture here:

"Seasons", as from Wikipedia

You'll notice that the Sun is as big as the Earth. But if you scale up the Sun to it's real size compared to the Earth, you would realize that the Earth would covered in daylight ALL THE TIME. So what's going on here?

//www.hoelymoley.com/questions/6967/-/6968 # 6968 16 答案由马特·霍尔为什么地球会不会“总是白天“如果“每日周期的阳光”是全面吗? 马特·霍尔 //www.hoelymoley.com/users/28050 2015 - 11 - 22 - t13:25:26z 2015 - 11 - 22 - t14:00:12z < p >太阳< a href = " https://en.wikipedia.org/wiki/Astronomical_unit " rel = " nofollow noreferrer " > < / >非常遥远。因此它的光线< a href = " https://physics.stackexchange.com/questions/155075/what-makes-suns-light-travel-as-parallel-beams-towards-earth " >基本上是平行< / >在地球的轨道。因此,尽管你贴的图是显然不太对劲的相对大小和太阳和地球之间的距离,平行光线是正确的。< / p > < p > < a href = " https://i.stack.imgur.com/L4pXa.png " rel = " nofollow noreferrer " > < img src = " https://i.stack.imgur.com/L4pXa.png " alt = "太阳和地球——公共领域图像" > < / > < / p > //www.hoelymoley.com/questions/6967/-/6969 # 6969 6 答案由戈登斯坦格为什么地球会不会“总是白天“如果“每日周期的阳光”是全面吗? 戈登斯坦格 //www.hoelymoley.com/users/4507 2015 - 11 - 22 - t19:11:03z 2015 - 11 - 22 - t19:11:03z < p >考虑到已知的平均距离太阳,太阳和地球的半径,基本三角法很简单。如果地球和太阳是完全相同的大小,和没有大气折射,然后一半地球,或180度,将照亮。但是由于太阳大得多,假设没有大气折射,然后180.522度的地球将会照亮。计算大气折射的阳光造成的额外的照明区域的黑暗是困难重重,因为变量大气霾雾,温度控制的空气密度的差异,和云分布。我猜你可以添加一个学位或两个如果你包括折射黄昏。< / p > //www.hoelymoley.com/questions/6967/-/6970 # 6970 11 回答Eubie画的地球为什么不“总是白天“如果“每日周期的阳光”是全面吗? Eubie画 //www.hoelymoley.com/users/4487 2015 - 11 - 22 - t20:19:45z 2015 - 11 - 22 - t21:23:26z < p >太阳100倍地球的大小(直径),和从地球到太阳的距离是大约100倍太阳直径的。<强> < em > < / em > < /强>是以下图片显示太阳、地球和它们之间的距离成比例。只不过它乍一看像是黑色的酒吧。这张照片在最初是<强> < em > 4000 < / em > < /强>像素(Pixlr的限制编辑)60像素,和地球小于一个像素。去看它的全图,< a href = " https://i.stack.imgur.com/YTpMm.png " rel = " nofollow noreferrer " >点击这里< / >或形象,当它出现在您的web浏览器中点击它再次放大到全尺寸。使用滚动条来看到太阳和地球另一端。你需要看<强> < em >真的< / em > < /强>密切关注地球。< / p > < p > < a href = " https://i.stack.imgur.com/YTpMm.png " rel = " nofollow noreferrer " > < img src = " https://i.stack.imgur.com/YTpMm.png " alt = "太阳、地球和它们之间的距离成比例,公共领域的图像“> < / > < / p > //www.hoelymoley.com/questions/6967/-/6976 # 6976 7 答案由乔恩·汉娜为什么地球会不会“总是白天“如果“每日周期的阳光”是全面吗? 乔恩·汉娜 //www.hoelymoley.com/users/4873 2015 - 11 - 23 - t11:11:00z 2015 - 11 - 23 - t16:36:02z < blockquote > < p >但如果扩大太阳实际尺寸与地球相比,< / p > < /引用> < p >是相当大的。然后以这种方式现实你还必须扩大从地球到太阳的距离。< / p > < p >但你甚至不需要这样做,因为有一个更简单的方法观察大太阳是地球上从一个位置的角度。李> < / p > < ol > <在或接近地球(你可能已经达到这个)。李李< / > < >看天空。< /李> < / ol > < p >如果是白天,而不是阴天你应该看到太阳某处(请不要继续找…)。它不是很大,大约32′(略有不同),只是略大于0.5°。< / p > < p >的月亮一样(或其他运输不会得到的款日食)。或公主的拇指大小的距离在公主的故事想要月亮作为生日礼物。< / p > < p >是不够的沐浴在太阳光线大部分的地球。只是足够的近一半被点燃,近一半是黑暗,并有一段给定的地球被一些,但不是全部,太阳的可见的圆盘。你可以看到同样的实验看看天空,通过向地平线在日出或日落。< / p > //www.hoelymoley.com/questions/6967/-/6977 # 6977 3 地球由周杰伦回答为什么不“总是白天“如果“每日周期的阳光”是全面吗? 周杰伦 //www.hoelymoley.com/users/4874 2015 - 11 - 23 - t14:55:44z 2015 - 11 - 29 - t21:31:36z < p >因为无论多么大太阳与地球相比,只有一半的地球可以面对太阳在任何给定的时间。< / p > < p >尝试画一个图,太阳对地球都要大得多。让它十倍或一百倍或者全力以赴,把它的规模。假设它是如此之大,它看上去不像一个圆环,只是无限长度的直线。不过,只有一半的地球正面临着在任何给定的时间。除非阳光可以穿透地球,或以某种方式泄漏边缘,地球仍然是黑暗的一半。< / p > < p > < em >更新< / em > < / p > < p >啊,我现在看到你来自哪里。好了,真的,如果太阳是无限大的,或者至少是非常大,非常接近,如果光离开了太阳表面上的任何点在各个方向旅行,那么是的,光线到达地球的部分不能面临向太阳。他们不能真正达到完全相反的一侧,但我想足够近。我承认,我想光线从太阳到地球的方向平行的一条直线从地球中心到太阳的中心。< / p > < p >我想所有离开太阳表面的光并不是直接从中心向外旅行,所以一定程度上,你的模型是合理的。坦白说我不够了解物理距离,类似于现实。 I'd think more light is travelling directly out from the center than at tangents, because the Sun is not a dark core with a thin glowing surface, but rather produces light from within. I have no idea what the relative numbers are though. But I guess the question is not the amount of light, but any light. So let's accept your model.

So yes, if the Sun was big enough and close enough, light from, say, the north pole of the Sun could hit a point on the "far side" of the Earth at a tangent. As in my diagram.

In real life, though, it's not THAT big or THAT close. Let's run the numbers.

enter image description here

Let $s$ be the distance from the Earth to the Sun, $r$ the radius of the Sun, and $A$ the angle along the curve of the Earth from the north pole. Then we have the triangle shown below, where $h$ is the height of the triangle. The radius of the Earth is very small compared to all the other numbers here, and so basically gets lost in the rounding. As $s$ is very large compared to $r$, $h$ is very close to $r$, so just to keep the geometry simple, let's assume $h=r$. (As $r \ge h$, calculating the real value for $h$ hurts your case.)

So geometry tells us that $r=s * \sin A$.

The Sun is about 93 million miles away. So for light rays in this scenario to reach 45 degrees past the Earth's north pole, we'd have:

$$ r = 93,000,000 * \sin(45) \\ r = 93,000,000 * \frac{\sqrt 2}{2} \\ r \approx 65,000,000 \\ $$

That is, the radius of the sun would have to be more than 65 million miles. In real life it's nowhere near that, it's more like 432,000.

So how far past the pole can the light really bleed?

$$ h \ge s * \sin A \\ \sin A \le h / s \\ \sin A \le \frac {432,000}{93,000,000} \\ \sin A \le .004645 \\ A \le 0.266 °\\ $$

That is, sunlight can "bleed" past the pole by about 1/4 of 1 degree.

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