Understand what a black hole is, what the event horizon is, and why not even light can escape, busting the main myths along the way.
Where there's no coming back
What a black hole is
If a dying star is truly massive, its core doesn't stop at the neutron star stage but keeps shrinking further and further — into a black hole. This is a region where matter is squeezed so tightly and gravity is so monstrous that nothing can escape from it — not even light. That's exactly why it is “black”: it emits nothing.
The event horizon is the point of no return around a black hole. While you're outside, you can still fly away if you're fast enough. But once you cross the horizon, there's no way back, like water already pulled over the edge of a waterfall. The boundary itself isn't a wall but a line: cross it, and that's it.
Important: we don't see the black hole itself (it's black, after all). But we do see hot gas swirling furiously around it before plunging in — it glows brightly. It's this glow that was photographed.
Lesson notes
What a black hole is
If a dying star is truly massive, its core doesn't stop at the neutron star stage but keeps shrinking further and further — into a black hole. This is a region where matter is squeezed so tightly and gravity is so monstrous that nothing can escape from it — not even light. That's exactly why it is “black”: it emits nothing.
The event horizon is the point of no return around a black hole. While you're outside, you can still fly away if you're fast enough. But once you cross the horizon, there's no way back, like water already pulled over the edge of a waterfall. The boundary itself isn't a wall but a line: cross it, and that's it.
Important: we don't see the black hole itself (it's black, after all). But we do see hot gas swirling furiously around it before plunging in — it glows brightly. It's this glow that was photographed.