What you are seeing is the first-ever image of a black hole. Maybe it doesn't look spectacular at first, but consider this: Black holes, by their very nature, are invisible because their gravitational pull is so strong that not even light can escape them. So for many years, astronomers thought that an image like this was impossible. How do you take a picture of something that does not emit light? Well, it starts with a small team of innovators and ends with a telescope that is unlike anything the world has ever seen.
How Astronomers Took the First Ever Image of a Black Hole
Now, despite major advances in telescope technology, there is no single telescope on Earth that can take a picture of a black hole. They're all too small. So astronomers innovated. If one telescope couldn't do the job, then perhaps eight would—and they were right.
They used eight radio telescopes, stationed at different points across the world, and kept them all in sync with powerful atomic clocks. They called the effort the Event Horizon Telescope. This series of telescopes combined has about the same capabilities as if you had build a telescope as large as our entire planet. And for the first time in history, it has shown us what a black hole, around 55 million light-years away, looks like.
This black hole is actually a supermassive black hole. It's about six and a half billion times as massive as our sun—that's enormous even compared to other supermassive black holes—and lives in the center of the Messier 87 galaxy. And as far as experts can tell, it looks exactly like what Einstein's general theory of relativity predicted. Here's a simulation of what the Event Horizon team thought the black hole would look like, and here's the real image. The light you see here is what's call the accretion disk. It's a disk of light that forms around the black hole when a star travels too close and is broken apart in the process. But the most important part of this photo is where there is no light—that dark circle in the center, which measures 25 billion miles across.
這個黑洞其實是一個超大質量黑洞。質量是太陽的六十五億倍－－與其他超大質量黑洞相比仍然非常巨大－－而這個黑洞位於 M87 星系中心。目前專家可以知道的是，這個黑洞與愛因斯坦廣義相對論中預測的黑洞長得一模一樣。事件視界團隊模擬的黑洞長這樣，而這是真實的黑洞。而你在這裡看到的亮光叫做吸積盤。這是一種光盤，圍繞著黑洞而形成的，當恆星太過靠近黑洞，就會被黑洞吸引並崩解，成為吸積盤的一部分。但這張照片最重要的部分就是沒有光的地方－－中間黑色圈圈的部份，直徑約二百五十億英里。
That, right there, is proof that black holes look and behave how astronomers thought, more specifically, that they actually have an edge. It's a place of no return, which astronomers call the event horizon. Once you cross the event horizon, the black hole's gravity is so strong that you cannot escape—not you, nor the fastest spacecraft, and not even the fastest thing in the universe: light. That's why the edge and everything beyond it are black, trapped inside the black hole's gravitational grip.
And this image may be just the beginning. The Event Horizon Telescope team has also turned its sights on another black hole, one that is closer to home, called Sagittarius A*. It's the supermassive black hole at the center of our own galaxy, the Milky Way, about 25 thousand light-years away. But it's significantly smaller than the one in Messier 87. So it will probably be more difficult to image. And since it took astronomers two years to combine and analyze data for this first image, it may be a while before we see what other black holes look like.
而這張照片可能只是個開始。事件視界望遠鏡團隊也將注意力放到另一個黑洞上，一個離地球比較近的黑洞，稱作「人馬座 A*」。這是在我們的銀河系中心的超大質量黑洞，距離我們兩萬五千光年遠。但這比 M87 的黑洞小得多。所以這可能會更難拍到。天文學家花了兩年組織並分析第一張照片的數據，因此我們可以想見，要看到另一張黑洞照片可能還需要等些時日。