托福听力背景知识天体篇，维夕独家讲解视频超全听力背景资料（comets vs planets）

托福听力讲座类lecture涉及到的话题范围很广选材众多，其中有不少话题因为具有较高的学术性，因此考生在缺乏专业背景知识的情况下，会感觉十分生僻冷门无法理解具体内容！！

维夕独家视频讲解,中英文翻译，高频真题，场景必考词汇统统都有！！

ETS最喜欢考的托福听力背景都在这里了，托福听力满分冲鸭~

今天给大家带来托福听力背景知识之——Astronomical Object--天体篇。

1、类地行星

类地行星是以硅酸盐石作为主要成分的行星。它们跟类木行星有很大的分别，因为那些气体行星主要是由氢、氦和水等组成，而不一定有固体的表面。类地行星的结构大致相同：一个主要是铁的金属中心，外层则被硅酸盐地幔所包围。表面一般都有峡谷、陨石坑、山和火山。

Terrestrial planets

A terrestrial planet is a planet that is composed primarily of silicate rocks or metals. Within the Solar System, the terrestrial planets are the inner planets closest to the Sun, i.e. Mercury, Venus, Earth, and Mars. Terrestrial planets have a solid planetary surface, making them substantially different from the larger giant planets, which are composed mostly of some combination of hydrogen, helium, and water existing in various physical states.

TPO 24 Lecture 4: Venus 金星

In other areas, you’ve got canyons, rift valleys, meteoric craters,uh,lava domes—these lava formations that look like giant pancakes—and also volcanoes…

在其他地区，有火山、轮廓清晰的山谷、陨石坑、熔岩穹丘，这些熔岩的形状就像是巨大的薄饼。

Well, one of the most interesting features on the surface are, in fact, the shield volcanoes.

火山也是如此，金星地表最有意思的特征是火山的地盾。

Shield volcanoes form when magma comes out of the ground in the same spot over and over again.

地盾是由于岩浆反复从一个地方喷出地表而形成的。

On Venus, however, volcanoes are not clustered in discrete zones like they’re on Earth. Instead, they’re more or less randomly scattered over Venus’ surface.

而在金星上，火山并不像在地球上一样在个别地区集中。相反地，它们很随机的分布在金星的表面。很是壮观，金星上大部分是盾状火山，它们的分布十分分散。

TPO 30 Lecture 3: Mars 火星

For example, one major discovery was that at one point water was present on Mars.How do we know?Well, in 2004, an exploration robot discovered jarosite there.

比如，一个重大发现是火星上有水。我们是怎么知道的？2004年，一个探索型机器人在火星上发现了黄钾铁矾。

Jarosite is a yellowish-brown mineral with a crystalline structure that's also found on Earth. It contains iron, potassium, and hydroxide.

黄钾铁矾是一种黄棕色的矿物质，其晶体结构在地球上也有。其中有铁、钾和氢氧化物。

The interesting thing is that on Earth at least, it needs highly acidic water to form.So we've got water... or had it at one point.

有趣的是，在地球上，需要酸性很强的水才能形成这种结构。所以我们有水，或一度曾有水。

2、小行星带

小行星带是太阳系内介于火星和木星轨道之间的小行星密集区域，由已经被编号的120,437颗小行星统计得到，98.5%的小行星都在此处被发现。这么多小行星能够被凝聚在小行星带中，除了太阳的引力作用以外，木星的引力起着更大的作用。

Asteroid Belte

The asteroid belt is the circumstellar disc in the Solar System located roughly between the orbits of the planets Mars and Jupiter. It is occupied by numerous irregularly shaped bodies called asteroids. About half the mass of the belt is contained in the four largest asteroids: Ceres, Vesta, Pallas, and Hygiea.

TPO 2 Lecture 4:：

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.

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。

And Ceres was in the right place - the missing spot. Uh, but it was way too faint to be a planet.

谷神星正好在那个空档里。嗯，但作为一颗行星它又太微弱。

Um, and so, Ceres was the first and is the largest of what became many objects discovered at that same distance.

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天体。

3、彗星

彗星（Comet）是进入太阳系内亮度和形状会随日距变化而变化的绕日运动的天体，呈云雾状的独特外貌。彗星分为彗核、彗发、彗尾三部分。彗核由冰物质构成，当彗星接近恒星时，彗星物质升华，在冰核周围形成朦胧的彗发和一条稀薄物质流构成的彗尾。彗星的质量、密度很小，当远离太阳时只是一个由水、氨、甲烷等冻结的冰块和夹杂许多固体尘埃粒子的雪球。当接近太阳时，彗星在太阳辐射作用下分解成彗头和彗尾，状如扫帚。

Comet

A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process called outgassing. This produces a visible atmosphere or coma, and sometimes also a tail. These phenomena are due to the effects of solar radiation and the solar wind acting upon the nucleus of the comet.

TPO 26 Lecture 3:

These are the comets that circle around the Sun pretty regularly.

有一些彗星非常有规律地环绕太阳运行。

They return again and again, predictably, after a certain period of time.That’s why we say their orbits are periodic.

根据预测，在一定时间之后，它们一次又一次的回来。这是为什么我们说他们的轨道是周期性的。

Probably the most famous and brightest of these is Halley’s comet.

它们之中最有名最明亮的也许是哈雷彗星。

Halley’s comet comes from far out in the solar system, goes in close to the Sun, and then out again.

哈雷彗星来自于太阳系较远的地方，运行到离太阳较近的地方，然后又再一次离开。

3、陨石／陨星

陨石是地球以外脱离原有运行轨道的宇宙流星或尘碎块飞快散落到地球或其它行星表面的未燃尽的石质、铁质或是石铁混合的物质。大多数陨石来自于火星和木星间的小行星带，小部分来自月球和火星。陨石大体可分为石质陨石、铁质陨石，石铁混合陨石。

Aristotle

A meteorite is a solid piece of debris from an object, such as a comet, asteroid, or meteoroid 流星体, that originates in outer space and survives its passage through the atmosphere to reach the surface of a planet or moon. When the object enters the atmosphere, various factors such as friction, pressure, and chemical interactions with the atmospheric gases cause it to heat up and radiate energy. It then becomes a meteor and forms a fireball.

TPO 13 Lecture 4:

Ok, I wanna go over the different types of meteorites, and what we have learned from them about the formation of Earth and solar system.

好的，我要讲一下各种不同的陨星，以及我们从这些陨星上获取的关于地球构造和太阳系的信息。

Uh... the thing is, what's especially interesting about meteorites is that they come from interplanetary space.

陨星特别有趣的一点是，这些陨星来自行星际空间。

But they consist of the same chemical elements that are in matter originated on Earth, just in different proportions.

但是他们包含着同样的起源于地球的化学元素，只是成分所占比例不同而已。

Meteoroids are…for the most part anyway…they are just smaller bits of asteroids and comets.

流星体在大多数情况下，它们是一小部分的小行星和彗星。

When these bits enter Earth’s atmosphere, well, that makes them so special that they get a special name.They are called “meteors.”

当这些碎片进入地球大气层之后，这就使它们变的特别，以至于会有一个特别的名字，称为流星。

Most of them are very small, and they burn up soon after entering the Earth's atmosphere.

大部分流星都体积很小，在进入大气层之后会很快燃烧起来。

The larger ones that make it through the atmosphere, and hit the ground are called meteorites.So meteorites are the ones that actually make it through.

那些体积较大，进入大气层之后直击地面的流星便叫做陨石。因此陨石其实就是那些穿透大气层到达地球表面的行星体。