Crash Course Astronomy: Black holes.

Crash Course Astronomy: Black Holes

Crash Course Astronomy: Black Holes

Bad Astronomy
The entire universe in blog form
Sept. 26 2015 9:00 AM

Crash Course Astronomy: Black Holes

black hole
Here's a place you don't want to be.

Drawing by NASA/JPL-Caltech

OK, so here’s the thing about black holes: They’re weird.

Phil Plait Phil Plait

Phil Plait writes Slate’s Bad Astronomy blog and is an astronomer, public speaker, science evangelizer, and author of Death From the Skies!  

Well, that’s not the only thing about black holes. And that’s the problem. There’s a lot to know about black holes, and it goes from simple to brain-melty pretty quickly. I had big plans for the Crash Course Astronomy episode about black holes, covering so many of the cool things about them.


After writing more than 3,000 words on them—the equivalent of about 25 minutes of footage—I realized I had a problem. A lot of stuff had to go. So I went through and cut this, excised that. What was left is, I hope, a pretty good primer on black holes, with the info you need to understand the basics.

The good news? Most of the stuff I cut will show up in later episodes. I’m pretty good about recycling electrons. If you’re impatient and want to know more about them now, then try these articles:

Oh, one more thing: In the video, at about the 8:30 mark, I talk about the perception of time near an object with gravity, and how it slows down. I say that someone near a black hole perceives time as moving more slowly than someone far away does. I should have phrased that differently; both people observe time to flow normally. To them. But they see each other's time flow rate change. Someone far away from the black hole sees the time flowing more slowly for the person near the black hole while the person close to the black hole sees the person's time far away flow more quickly. Time is relative; grammar isn't. I should've been more clear.