I'm John Batchew with Ken Croswell, the astronomer, a new discovery that black holes operate alone,

wandering the universe, looking for a reason for being perhaps.

But there are many of them, and Ken points to the possibility that one is near at hand,

50 light years, which is next door.

How do they come to, they haven't found it yet, I understand, but they believe something's out there.

How do they know that, Ken?

Well, take that number that I mentioned, that we estimate based on the lives and depths of these massive stars that leave behind black holes.

And think of all the massive stars that have lived in the 13 billion year life of the Milky Way, there's going to be a lot of black

holes left behind. So we think there are something like 100 million black holes total in our

galaxy alone.

And so you can just say, well, okay, let's suppose those black holes are distributed more or less

the way the ordinary stars of the Milky Way are.

How close do we expect the nearest black hole to Earth to be?

And when you do that calculation, you find that,

well, probably nearest black holes within 50 light years of the sun. Now, that's actually

pretty close as things go. For comparison, Alpha Centauri, which is the nearest star system, is 4.3 light years from Earth.

And so that means the nearest black hole is only about 12 times as far as the nearest star system to the sun.

Now, if you want to know, okay, what is the nearest black hole that we have actually discovered?

It's a lot farther than 50 light years.

The nearest black hole was discovered by the Gaia Space Telescope just three or four years ago,

and it is located 1560 light years from Earth.

So that's a lot farther than 50 light years.

...