In the northern hemisphere, summer began at 5:28 AM MDT (11:28 UTC).
It’s the longest day of the year for locations north of the equator. The further north, the more daylight. That means 14 hours and 31 minutes of daylight in Albuquerque, 14 hours and 59 minutes in Denver, Colorado, 15 hours and 44 minutes in Billings, Montana, and 21 hours 50 minutes in Fairbanks, Alaska.
[Sunrise today in Fairbanks was at 2:57 AM. Sunset tonight will be at 12:47 AM Tuesday. Of course, with twilight, it is light all night.]
What this means astronomically speaking is that at 06:46 Universal Time today (June 21) the northern hemisphere of the earth was tilted 23.4° toward the sun; the southern hemisphere was tilted 23.4° away.
This is best explained with an orange and a flashlight.
