DK Space a Visual Encyclopedia smithsonian太空视觉百科全书

What is space? We live on a small blue planet called Earth. It has a surface of liquid water and rock and is surrounded by a blanket of air called the atmosphere.
什么是空间？我们生活在一个叫地球的蓝色小星球上。它的表面是液态水和岩石，周围是一层称为大气的空气。
Space begins at the top of the atmosphere. It is an unimaginably vast, silent, and largely empty place, but it has many amazing properties.
太空从大气层的顶部开始。这是一个无法想象的广袤、寂静、空旷的地方，但它有许多惊人的特性。 THE EDGE OF SPACE Earth’s atmosphere does not end suddenly—it gets gradually thinner and thinner as you travel up from the ground. Most experts agree that outer space starts at a height of 62 miles (100 km).
太空的边缘地球的大气层并不是突然结束的，当你从地面上升时，它会变得越来越薄。大多数专家都同意外层空间始于62英里（100公里）的高度。
Yet even above this height, there is a layer of very thin air called the exosphere. Hydrogen and other light gases are slowly escaping into space from this outermost part of Earth’s atmosphere.
然而，即使在这个高度以上，也有一层非常薄的空气，称为外大气层。氢和其他轻气体正慢慢地从地球大气层的最外层逃逸到太空中。 Blacker than black Planets like Earth shine because they reflect light from the Sun. Stars shine because they produce huge amounts of energy by burning fuel.
比像地球这样的黑色行星更黑的行星发光是因为它们反射太阳光。恒星发光是因为它们通过燃烧燃料产生巨大的能量。
In photos taken from space, our planet is surrounded by blackness. Most of space looks dark or black because the universe is very vast, and light from distant objects is traveling from so far away that they are barely visible to the naked eye.
在太空拍摄的照片中，我们的星球被黑暗所包围。大部分空间看起来都是黑色或黑色的，因为宇宙非常广阔，而来自遥远物体的光从很远的地方传播，肉眼几乎看不见。 IN A VACUUM A place without any air or gas is called a vacuum. On Earth, air transfers heat from one place to another. As there is very little gas to distribute heat in the emptiness of space, it is nearly a vacuum.
在真空中，没有空气或气体的地方称为真空。在地球上，空气将热量从一个地方传递到另一个地方。由于在空旷的太空中几乎没有气体来散发热量，所以它几乎是一个真空。
In space, the sunlit side of a spacecraft gets very hot, while the other side is in darkness and gets very cold. Spacecraft have to be tested in a thermal vacuum chamber before they are launched to make sure that they can survive these
在太空中，航天器的阳光照射一侧变得非常热，而另一侧处于黑暗中，变得非常冷。航天器在发射前必须在热真空室中进行测试，以确保能够在这些环境中生存 Getting off the ground It is difficult to get into space because Earth’s gravity holds everything down. To overcome gravity and go into orbit, a rocket has to reach a speed of 17,500 mph (28,000 kph), which requires a lot of fuel to provide energy.
离开地面很难进入太空，因为地球的引力把所有东西都压下来了。为了克服重力进入轨道，火箭必须达到17500英里/小时（28000公里/小时）的速度，这需要大量燃料来提供能量。
To reach the Moon and planets, spacecraft have to travel at an even higher speed—25,200 mph (40,000 kph), known as escape velocity.
为了到达月球和行星，宇宙飞船必须以更高的速度飞行——25200英里/小时（40000公里/小时），即逃逸速度。 Our place in space Planet Earth is our home, and to us it seems like a very big place. Flying to the other side of the world takes an entire day, and sailing around the world takes many weeks.
我们在太空中的位置——地球是我们的家，对我们来说，它似乎是一个非常大的地方。飞到世界的另一边需要一整天，而环球航行则需要好几个星期。
Yet in the vastness of the Universe, Earth is just a tiny dot. In fact, an alien flying through our galaxy would probably not even notice our little planet.
然而，在浩瀚的宇宙中，地球只是一个小点。事实上，一个外星人飞过我们的银河系，可能根本不会注意到我们的小星球。