1、这个事是托福 tpo2 的最后一篇。内容为天文学。天文学是一个很神奇的学科，其中的词汇也是比较多的。其中有许多词汇都不需要记住（记住了肯定是有些好处的） 。听的时候要求注意可能设问的地方。反复去听。上课的时候会从中设问，要求回答。别忘了按时完成作业，按时打卡。TPO 2 Lecture 4 AstronomyNarratorListen to part of a lecture in an astronomy class. You will not need to remember the numbers the professor mentions.ProfessorOK. Lets get
2、 going. Today I m going to talk about how the asteroid(小行星) belt（腰带）was discovered. And . . . Im going to start by writing some numbers on the board. Here they are: Well start with zero, then 3, . . . 6, . . . 12. Uh, tell me what Im doing.Female （女性的）studentMultiplying（乘） by 2?ProfessorRight. Im do
3、ubling the numbers, so 2 times 12 is 24, and the next one Im going to write after 24 would be . . .Female student48.Professor48. Then 96. Well stop there for now. Uh, now Ill write another row of numbers under that. Tell me what Im doing. 4, 7, 10 . . . How am I getting this second row?Male StudentA
4、dding 4 to the numbers in the first row.ProfessorIm 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 Im doing.Female StudentPutting in a decimal?ProfessorYes, I divided （除）all those numbers by 10 by putting in a decimal（十进制的） po
5、int. Now Im going to write the names of the planets （行星）under the numbers. Mercury . . . Venus. . . Earth. . . Mars. So, what do the numbers mean? Do you remember from the reading?Male StudentIs it the distance of the planets from the Sun?ProfessorRight. In astronomical （天文学的）units（单元）not perfect, b
6、ut tantalizingly （非常）close. The value for Mars is off （偏移）by . . . 6 or 7 percent or so. Its . . . but its within 10 percent of the average distance to Mars from the Sun. But I kind of have to skip （略过）the one after Mars for now. Then Jupiters right there at 5-point something, and then Saturn is abo
7、ut 10 astronomical units from the Sun. Um, well, this pattern（模式） is known as Bodes Law（定律）. Um, it isnt really a scientific law, not in the sense of predicting（预测） gravitation（引力） mathematically or something, but its attempting（试图找到） a pattern in the spacing（分布） of the planets, and it was noticed b
8、y 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（忽略）, and um . . . but there wasnt anything obvious （明显） there, in the early telescopes（望远镜）. Then what happened in the late 1700s? The discovery of . . . ?Female StudentAno
9、ther planet?ProfessorThe next planet out, Uranusafter 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（证实） of this thing and finding the missing （遗失的）object between Mars and Jupiter. An
10、d 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 was discovered. And Ceres was in the right placethe missing spot（位置）. Uh, but it was way too faint （模糊）to be a planet. It loo
11、ked like a little star. Uh, and because of its starlike（类似于星星的） appearance, um, it was called an “asteroid（小行星）.” OK? “Aster” is Greek （希腊语）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 from the asteroid belt. So the asteroid belt is the most famous success of this Bodes Law. Thats how the asteroid belt was discovered.我的博客：
