載入中... 相關課程 Back Supernova clarification 登入觀看 ⇐ Use this menu to view and help create subtitles for this video in many different languages. You'll probably want to hide YouTube's captions if using these subtitles. Supernova clarification 上傳學習單 下載學習單 相關課程 0 / 750 I want to make one clarification on my video on super, or actually I should say supernovae, because that's the plural for supernova, is that I said this supernova occurred a thousand years ago. That's actually not precisely right. The supernova was first observed 1,000 years ago. Or the light from that first explosion was observed by astronomers, we believe, 1,000 years ago. But we have to be very clear here because the Crab Nebula, and its core is roughly 6,500 light years away. Even this light, even this image we see right here is that nebula as it was 65 hundred years ago. And so the supernova itself, if you think about when it actually occurred, it actually must have occurred about 75 hundred years ago. So it must have occurred about 75 hundred years ago, years ago, and that first light, from that first explosion from that first energetic event reached us about a thousand years ago. So it took 65 hundred years to get to us, and reached us a thousand years ago. So first, first light 1,000 years ago, 1,000 years. I just wanted to make that clear, it might have been obvious to some of you all, but always important to think about it. When I said a thousand years ago, I really should have said it was first observed, the explosion was observed a thousand years ago. But since it's so far, the actual event must have occurred 75 hundred years ago.