Tomorrow in the northern hemisphere we will experience the summer solstice. The southern hemisphere is, of course, experiencing the winter solstice.
For the bulk of humanity who live north of the equator, tomorrow is the longest day (and shortest night) of the year. Starting tomorrow the days begin getting shorter, a process that will continue until December 21.
Here in Wyoming twilight will disappear after 10 p.m. tonight. North of here in Jasper, Alberta, Canada, tonight it will disappear after 11 p.m.
I stepped outside my RV in Fairbanks, Alaska, at 1 a.m. on June 21 some 30 years ago. We were so close to the Arctic Circle I was able to read a newspaper without artificial light, albeit with much younger eyes.