How much of the sun needs to be blocked in order to see a noticeable drop in brightness I live in NYC and just experienced the eclipse. What fascinated me the most was that despite the fact that the sun was about 70% blocked, the area was not noticeably dimmer. If the news wasn't saying there was a solar eclipse I wouldn't have realized it was happening.

How much of the sun needs to be blocked by the moon in order to noticeably dim an area?
Based on the CNN's reporting it appeared to get noticeably darker at near 95% coverage. That's just from watching the onset of darkness for locations experiencing totality.