1Hi, it's Doug!
2This is the first ever real photograph of a black hole.
3Now, seeing this makes me think of all kinds of questions, like...
4why haven't we been able to take a photograph of this before?
5Someone named Sammy has a question about this, too.
6Let's give her a call now.
7Hi Doug.
8Hey, Sammy.
9I have a question for you.
10What is a black hole?
11That is a great question.
12Well, I've gotta tell you, this is one of the most surprising questions in science
13because a black hole sounds like it might be a simple thing to explain.
14It's some kind of hole, right?
15But the idea of a black hole is one of the most advanced and maybe one of the weirdest ideas in all of science.
16For starters, a black hole is not actually a hole at all.
17It's an object, a thing.
18So, what kind of thing is a black hole?
19Well, at first it was just something that scientists imagined could exist.
20It was just an idea, a what-if.
21So what's the idea of a black hole?
22Well, you know how the Earth has gravity, right?
23We think of gravity as the invisible force that keeps everything pulled down.
24You can jump up and get off the Earth's surface,
25but only for a second or two.
26Gravity pulls you back down.
27It's not that we can't escape the Earth's gravity.
28You know we can send things to space,
29but to do that we need to go really fast.
30A rocket has to travel at a speed of nearly 25,000 miles an hour
31in order to get to outer space.
32We call this escape speed.
33Earth isn't the only thing in space that has gravity.
34Mars has gravity, the Moon has gravity, too.
35Now, because the moon is smaller than the Earth or less massive,
36it turns out the Moon has less gravity than the Earth.
37If you jump while standing on the Moon,
38you go a bit higher before the Moon's gravity pulls you all the way back down to the surface.
39This also means that the Moon's escape speed is much less than the Earth.
40Rockets don't have to fly as fast to escape the Moon.
41The Moon's escape speed is only about 5,000 miles an hour.
42Okay, that's the moon though.
43What about an object more massive than the Earth?
44If you could stand on a planet bigger than Earth,
45the gravity would be stronger.
46You wouldn't be able to jump as high as you can on Earth.
47And the escape speed would be even more than the Earth's escape speed.
48This is where the idea of a black hole comes in.
49Scientists asked themselves,
50what if there were an object so massive,
51an object that had such strong gravity
52that not even the fastest thing in the universe would have enough speed to escape it?
53Let's think about what this might be like.
54What even is the fastest thing in the universe?
55Before I say anything more, try to take a guess.
56The fastest known thing in the universe is light.
57Maybe not too surprising, right?
58When you turn on a light switch,
59the time it takes for light to go from the light bulb to your eyes seems like it happens instantly.
60What if there were an object with such strong gravity
61that its escape speed was even higher than the speed of light?
62Would that mean even light itself wouldn't be fast enough to escape this object?
63If you think about it, you can start to imagine why the name black hole makes a pretty good name for this idea.
64It would be like a hole because an object like this would have such strong gravity,
65anything that got anywhere near it would get sucked in towards it.
66A passing spaceship, nearby planets, entire stars,
67maybe even light itself.
68If light couldn't escape an object like this, think of just how weird that would be.
69Imagine if you could stand on this object with a flashlight.
70You go to point the flashlight up to shine it into space,
71but the gravity of the object would be so strong
72that the light wouldn't even be able to go up.
73It would bend back and fall toward the ground beneath you.
74So the object itself would have to look black.
75It would suck in any light that got near it.
76Now, like I said, at first all of this was just an idea, a what-if.
77If such a thing existed, would it really do that to light?
78Can light really be bent?
79But around the middle of the 1900s,
80scientists discovered some reasons for thinking that black holes might actually exist in real life.
81They started looking for them using telescopes.
82But as you might expect,
83one reason why it'd be hard to see a black hole is because they're black,
84and so is outer space,
85but it should be possible,
86especially if there's a black hole sucking in material from some nearby object like a star.
87Maybe we'd see a bunch of light getting sucked in to a kind of black spot and disappearing.
88Using telescopes, scientists started finding places in the universe where they think some black holes might exist.
89None of these places are anywhere near us, which is good news.
90We wouldn't want to get pulled into one.
91But this is also the main reason why it's been so hard to actually get a photograph of one.
92Even though a black hole is a massive object,
93they're all so far away from us that scientists realized...
94we would need a telescope the size of the Earth itself just to be able to see one.
95That is what's most amazing about this, the first ever actual image of a black hole.
96A team of 200 astronomers worked together all around the globe
97and used eight different telescopes
98to basically act like one giant Earth-sized telescope.
99It was not an easy thing to do.
100Not only did the telescopes all have to point at the exact same place in space,
101but to combine the view from each telescope involved really advanced computer skills
102used by scientists like Katie Bouman.
103Now we have photographic proof.
104Black holes aren't just an idea, they're a real thing.
105What other kinds of strange things will we be able to discover by combining telescopes like this?
106Will we be able to actually see other planets like Earth going around faraway stars?
107Will we be able to find other things we've only imagined could be real in movies and stories?
108Things like wormholes, passageways that take us to other parts of the galaxy.
109One thing's for sure, it's an exciting time to be alive.
110That's all for this week's question.
111Thanks Sammy for asking it.