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Bode's Law

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What is Bode's law?
• A. A law of gravitation

• B. An estimate of the distance between Mars and Jupiter

• C. A prediction of how many asteroids there are

• D. A pattern in the spacing of the planets

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NARRATOR:Listen to part of a lecture in an astronomy class. You will not need to remember the numbers the professor mentions.

MALE PROFESSOR:OK. Let's get going. Today I'm going to talk about how the asteroid belt was discovered. And... I'm going to start by writing some numbers on the board.Here they are; We'll start with zero, then 3, ... 6, ... 12. Uh, tell me what I'm doing.

FEMALE STUDENT:Multiplying by 2?MALE PROFESSOR:Right, I'm doubling the numbers, so 2 times 12 is 24, and the next one I'm going to write after 24 would be...

FEMALE STUDENT:48

MALE PROFESSOR:48 [slowly, as if just being calculated and written on the board]. Then 96 [slowly, as if just being calculated]. We'll stop there for now. Uh, now I'll write another row of numbers under that. Tell me what I'm doing.4, 7, 10... How am I getting the second row?

MALE STUDENT:Adding 4 to the numbers in the first row.

MALE PROFESSOR:I'm adding 4 to each number in the first row to give you a second row. So the last two will be 52, 100, and now tell me what I'm doing.

FEMALE STUDENT:Putting in a decimal?

MALE PROFESSOR:Yes, I divided all those numbers by 10 by putting in a decimal point.Now I'm going to write the names of the planets under the numbers. Mercury... Venus... Earth... Mars.So, what do the numbers mean? Do you remember from the reading?

MALE STUDENT:Is it the distance of the planets from the Sun?

MALE PROFESSOR:Right. In astronomical units - not perfect, but tantalizingly close.The value for Mars is off by... 6 or 7 percent or so. It's... but it's within 10 percent of the average distance to Mars from the Sun.But I kind of have to skip the one after Mars for now.Then Jupiter's right there at 5-point something, and then Saturn is about 10 astronomical units from the Sun.Um, well, this pattern is known as Bode's Law.

Um, it isn't really a scientific law, not in the sense of predicting gravitation mathematically or something, but it's attempting a pattern in the spacing of the planets, and it was noticed by Bode hundreds of years ago.Well, you can imagine that there was some interest in why the 2.8 spot in the pattern was skipped, and um... but there wasn't anything obvious there, in the early telescopes. Then what happened in the late 1700s? The discovery of...?

FEMALE STUDENT:Another planet?

MALE PROFESSOR:The next planet out, Uranus - after Saturn. And look, Uranus fits in the next spot in the pattern pretty nicely, um, not perfectly, but close.

And so then people got really excited about the validity of this thing and finding the missing object between Mars and Jupiter. And telescopes, remember, were getting better. So people went to work on finding objects that would be at that missing distance from the Sun, and then in 1801, the object Ceres [SI-reez] was discovered.

And Ceres was in the right place - the missing spot. Uh, but it was way too faint to be a planet. It looked like a little star. Uh, and because of its star-like appearance, um, it was called an "asteroid".OK? "Aster" is Greek for "star", as in "astronomy".Um, and so, Ceres was the first and is the largest of what became many objects discovered at that same distance. Not just one thing, but all the objects found at that distance form the asteroid belt.So the asteroid belt is the most famous success of this Bode's Law.That's how the asteroid belt was discovered.

• 旁白：听一段天文学课堂的讲座。你不需要记住教授提到的数字。

教授：好了，咱们现在开始。今天我将说说小行星带是如何被发现的。同时……我们将从黑板上的这些数字开始。开始写了：我们从0 开始，接着是3，6，12……说说我在做什么？

学生：（所得值）乘以2？教授：不错。我在使这些数翻倍，所以2 乘以12 是24，24 之后我要写的数是……

学生：48

教授：48，然后是96。我们暂时停一下。现在我在这一组数字下面写另外一组数字。说说我在干什么？4,7,10……第二组数字我是怎么得到的？

学生：在第一组数字后面加上4。

教授：现在我给第一组数字的每一个数值加4 得出第二组。所以，那就是52，100，说说我在做什么？

学生：十进位排序？

教授：是的，我用加小数点来表示将这些数除以10。我现在在这些数字下面写上行星的名字。水星、金星、地球、火星。这样看来，这些数字又是什么意思？你们能记住这些读数吗？

学生：是从这些行星到太阳的距离吗？

教授：是的。用天文单位计算——不算完美，但极为接近了。就拿火星到太阳的距离来说可能偏差6%到7%。但……误差应该在10%以内。但我要暂时先跳过火星后的这颗行星。然后这边的木星到太阳有5 个天文单位左右的距离，之后土星到太阳的距离大概有10 个天文单位。这个规律就是众所周知的波德定律。

嗯，这不是一个真正意义上的科学定律，并不在预测重力数值之类的层面，而是在尝试测量星球之间的距离，它在几百年前被波德发现。你们可以设想一下，这里有点意思：为什么跳过了2.8 个点？嗯……但这在早期的望远镜中并不明显。那么在18 世纪末发生了什么？发现了……？

学生：又一个行星？

教授：下一个行星显现，天王星——在土星之后。天王星放在下面这个空档里倒是很合适，嗯，尽管谈不上十分精准，但已经非常接近。

后来，人们对这个数值的准确性变得很感兴趣，同时寻找火星和木星之间缺失的天体。还记得，望远镜也变得越来越好了吗？所以人们从那个空档到太阳间寻找缺失的天体，后来到1801 年，谷神星被发现。

谷神星正好在那个空档里。嗯，但作为一颗行星它又太微弱。它看起来像一颗小星，因为它具备星型特征，所以它被称作“小行星”明白吗？“Aster”是希腊文，指“星星”，“天文学”这个词也有。嗯，那么，谷神星是第一个也是在同一距离发现的天体里面最大的行星。不是单一物体，而是在那个距离里发现的所有物体共同形成小行星带。小行星带是波德定律里最成功的（假设）。小行星带就是这样被发现的。

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解析

题型分析：细节题

题干分析：题干提问一个学术名词，确定为细节题，根据Bode's Law定位到原文。

原文定位

Then Jupiter’s right there at 5-point something, and then Saturn is about 10 astronomical units from the Sun. Um, well, this pattern is known as Bode’s Law.

选项分析

本文开头有很多数字和小数点，很有可能把人绕晕。但文章的开头已经有了提示，不需要记住这些数字，说明数字不是重要信息。原文提到Saturn距离Sun有10个天文单位，随后总结说这就是Bode's Law。可见，这个Law是跟举例有关系的，故此选D。D选项，space是空间，spacing有空间排布的意思。

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