Title text:
I've had countless nights where the line never left the bottom zone of the graph, but the few moments where it's climbed all the way to the top have made up for them all.
Transcript:
Transcript will show once it’s been added to explainxkcd.com
Source: https://xkcd.com/3196/
This is accurate. The best I ever saw lasted about 2 minutes, after hours of sitting watching basically nothing. Everyone else had long gone inside but I still had my camera set. Absolutely worth sitting alone on a hillside, it was by far the most amazing thing I've ever witnessed.
It also helps to let your eyes accustom to the dark, IIRC 45 minutes is ideal.