38 Powerful Telescopes-Mid

Powerful Telescopes FOCUS Question How do telescopes help us see far into the universe?

强大的望远镜焦点问题望远镜如何帮助我们看到宇宙深处?

Looking into Space Are there planets outside our solar system? What are stars made of? Is there a black hole at the center of the Milky Way galaxy? How big is the universe? Astronomers rely on a very important type of tool to help answer these questions: the telescope. Telescopes allow us to see distant objects They magnify these objects. so that they appear bigger than they do when you look at them with the naked eye. There are many different types of telescopes. Some use mirrors to collect light, while others use glass lenses. Some collect visible light, while others detect light that we can't see. Some make observations from Earth, while others are out in space.

太阳系外有行星吗? 恒星是由什么构成的?在银河系的中心有一个黑洞吗? 宇宙有多大?天文学家依靠一种非常重要的工具来帮助回答这些问题:望远镜。 望远镜使我们能看到远处的物体。它们把这些物体放大。 所以它们看起来比你用肉眼看到的要大。 有许多不同类型的望远镜。 有的用镜子收集光线，有的用玻璃镜片。 有些收集可见光，有些则探测我们看不见的光。 一些人在地球上进行观测，而另一些人则在太空中。

Refracting Telescopes The first known telescope was invented in 1608. In 1609, Thomas Harriot and Galileo Galilei used telescopes to look into the sky. They were amazed at what they saw. Harriot drew maps of the Moon with details not seen before. Galileo discovered four moons orbiting the planet Jupiter. Soon, scientists were building more powerful telescopes to observe objects in the sky. Galileo's telescope was a refracting telescope. In a refracting telescope, light first travels. through a piece of curved glass called a lens The curve of the lens. causes the light to bend, or refract. Light rays pass through a tube, come together, and pass through a second lens. The second lens refracts the light again before it passes into the eye. The eye sees a large image of the object.

第一架望远镜发明于1608年。 1609年，托马斯·哈里奥特和伽利略·伽利莱用望远镜观测天空。 他们被眼前的景象惊呆了。 哈里奥特绘制了月球地图，其中包含了以前从未见过的细节。 伽利略发现了环绕木星运行的四颗卫星。 不久，科学家们开始建造更强大的望远镜来观测天空中的物体。 伽利略的望远镜是折射望远镜。 在折射望远镜中，光首先传播。 通过一块叫做透镜的弯曲玻璃透镜的曲线 使光弯曲或折射。 光线穿过一根管子，聚集在一起，然后穿过第二个透镜。 第二个晶状体在光线进入眼睛之前再次折射。 眼睛看到的是物体的大图像。

Reflecting Telescopes Early refracting telescopes had some problems. It was hard to grind the glass lenses perfectly, so the images were often fuzzy and the colors were not quite right. In 1668, Isaac Newton invented the reflecting telescope. These telescopes use mirrors instead of lenses to gather light. In a reflecting telescope, light from the object travels through the telescope and reflects, or bounces off, a curved mirror. The curved mirror focuses light to a small point, where there is another, smaller mirror. The light then bounces off that mirror and travels to the eye. Most large modern telescopes are reflecting telescopes. Compare the telescope diagrams on pages 3 and 4.

反射望远镜早期的折射望远镜存在一些问题。 玻璃镜片很难磨得很完美，所以图像经常模糊，颜色也不太正确。 1668年，艾萨克·牛顿发明了反射望远镜。 这些望远镜用镜子而不是透镜来收集光线。 在反射式望远镜中，物体发出的光穿过望远镜，在曲面镜上反射或反射回来。 曲面镜将光线聚焦到一个小点上，在这个小点上还有另一个更小的镜子。 然后光线从镜子反射到眼睛。 大多数大型现代望远镜都是反射望远镜。 比较第3页和第4页的望远镜图。

Invisible Forms of Light Objects in space give off many different forms of light, or electromagnetic radiation. We can see visible light, but we can't see the other forms of light. These include radio waves microwaves, infrared, ultraviolet, X-rays, and gamma rays. Engineers have designed telescopes that detect these invisible forms of light. For example, the Goldstone radio telescope in California collects radio waves from space. Radio telescopes help us search for signs of intelligent life in the universe. The image to the right is from the Chandra X-Ray Observatory in space. It shows X-rays from an exploding star called Kepler's Supernova. The image uses false colors. Each color represents a different X-ray wavelength.

太空中的物体会发出许多不同形式的光，也就是电磁辐射。 我们能看到可见光，但我们看不到其他形式的光。 这些包括无线电波、微波、红外线、紫外线、x射线和伽马射线。 工程师们设计了望远镜来探测这些看不见的光。 例如，加州的戈德斯通射电望远镜收集来自太空的无线电波。 射电望远镜帮助我们寻找宇宙中智慧生命的迹象。 右边的图片来自太空中的钱德拉x射线天文台。 它展示了一颗名为开普勒超新星的爆炸恒星发出的x射线。 图像使用了错误的颜色。 每种颜色代表不同的x射线波长。

Earth-Based Telescopes: The Bigger, the Better Increasing the size of a telescope's mirror usually leads to a more powerful telescope. Bigger reflectors gather more light. They allow us to see objects that are much smaller, fainter, or farther away than smaller telescopes do. However, it is very hard to make large mirrors that are perfectly shaped. Also, their weight causes them to bend. Then the light does not bounce off the surfaces in the right direction. The images become distorted. To avoid this problem, engineers often make mirrors that are actually many smaller mirrors put together. The large mirror of the Southern African Large Telescope (SALT) is made of 91 mirrors, each of which is 1.2 meters (4 ft.) across Together, they make a mirror that is 11 meters (36 ft.) by 9.8 meters (32 ft.) It can help us see objects that are one billion times fainter than what you can see when you look at the sky.

地面望远镜:越大越好增大望远镜反射镜的尺寸通常会使望远镜性能更强。 更大的反光镜能聚集更多的光。 它们使我们能够看到比小型望远镜更小、更暗淡或更远的物体。 然而，要做出形状完美的大镜子是非常困难的。 此外，它们的重量使它们弯曲。 这样，光线就不会以正确的方向从表面反弹。 图像变得扭曲。 为了避免这个问题，工程师们经常把很多小镜子放在一起制成镜子。 南部非洲大型望远镜(SALT)的大镜子由91个镜子组成，每个镜子的直径为1.2米(4英尺)，它们组成了一个11米(36英尺)乘9.8米(32英尺)的镜子。它可以帮助我们看到比我们在天空中看到的物体要微弱10亿倍的物体。