Black Holes黑洞
A black hole is a place in space where gravity is so strong that nothing can escape, not even light.黑洞是太空里的一个地方，那里的引力强得什么都逃不出去，连光也不行。
See it in 3D去看3D版Simple explanations简单说一说
How is one born?黑洞怎么来的？
Some very big stars run out of fuel and collapse. Then a black hole can form.有些特别大的恒星燃料用完后会塌缩，这时就可能形成黑洞。
Can we see one?能看到黑洞吗？
A black hole is dark, so we find it by how it moves nearby stars and gas. In 2019, scientists shared the first picture of a black hole’s shadow. It was made from radio telescope data.黑洞是黑的，所以我们通过它怎样影响附近的恒星和气体来找到它。2019年，科学家公布了第一张黑洞“阴影”的图像，它是用射电望远镜的数据合成的。
Is Earth in danger?地球有危险吗？
No. The closest black holes we know are more than 1,000 light-years away. Our Sun is too small to become one.没有。我们已知最近的黑洞也在1000多光年之外，太阳也不够大，变不成黑洞。
An open question一个还没解开的问题
What is deep inside a black hole? Nobody knows for sure yet. Our best science of gravity stops working there, so scientists are still searching for answers.黑洞最深处是什么样？现在还没有人确切知道。我们现有最好的引力理论在那里就不管用了，所以科学家还在继续寻找答案。
Fly toward a black hole飞向黑洞
Pretend you are in a spaceship. Slide to fly toward a black hole.假装你坐在一艘飞船里。拖动滑块，飞向一个黑洞。
Far away很远的地方
From here, a black hole pulls on you about as much as any object of the same weight. You could safely orbit it.从这么远的地方看，黑洞对你的拉力和同样重的其他天体差不多，你可以安全地绕着它转。
Closer靠近一些
The pull gets stronger. Gas and dust swirl around in a bright, hot disk.拉力变强了。气体和尘埃围着它旋转，形成又亮又热的圆盘。
Closer still更近了
Gravity bends light around the black hole, so the stars behind it look warped.引力把黑洞周围的光线弯折，所以它后面的星星看起来都变形了。
Very close非常近了
Your spaceship needs more and more speed to stay away. The pull on your feet is stronger than on your head, so you would feel stretched.飞船需要越来越快才能不被拉进去。脚受到的拉力比头大，你会被拉长。
The edge: event horizon边界：事件视界
This is the point of no return. Inside it, nothing comes back out, not even light. What happens deep inside is still a mystery that scientists study with maths.这是“有去无回”的边界。进去以后什么都出不来，连光也不行。里面深处到底发生了什么，仍是个谜，科学家在用数学研究它。
This is a made-up journey drawn to help you imagine it. Real black holes are very far away.这是为了帮助想象而画的虚构旅程。真正的黑洞都离我们非常远。
Did you know?你知道吗？
- Scientists think most big galaxies have a huge black hole in the middle. Ours is called Sagittarius A*.科学家认为大多数大星系的中心都有一个巨大的黑洞。银河系中心的那个叫人马座A*。
Quick quiz小测验
What cannot escape a black hole?什么东西逃不出黑洞？
Gravity near a black hole is so strong that light cannot get out.黑洞附近的引力非常强，连光也逃不出来。
Will our Sun become a black hole?我们的太阳会变成黑洞吗？
Only much bigger stars end their lives as black holes.只有比太阳大得多的恒星，才会在生命的最后变成黑洞。
How do scientists find black holes?科学家怎样发现黑洞？
Black holes are dark, so we spot them by their effects on things around them.黑洞是黑的，所以我们通过它对周围物体的影响来发现它。