As a former third baseman who never played under the lights, I remember many evenings hoping for just a few more minutes of natural light so we could squeeze in that last inning.

Officially, the sun sets here around 8:30 this evening, but of course it won't necessarily get dark then. Twilight is the period after sunset when some light is being bent around the curvature of the earth. There is also early morning twilight, in the pre-dawn hours before sunrise, for the same reason.

Twilight can be defined a few ways, depending on how far the sun is below the horizon. So-called civil twilight lasts in the evening until the center of the sun drops 6 degrees below the horizon. Around here, that translates into about 30 minutes after sunset when it's still bright enough, barring any cloud cover, to squeeze in that last inning. This evening, civil twilight lasts until about 9:05, more than half an hour after the sun officially sets.