National Geographic tells us that,
For Americans, summer will begin either on Thursday or Friday—depending on which time zone you live in. That’s because the timing of the summer solstice depends on when the sun reaches its farthest point north of the equator, and that varies from year to year.
EarthSky has some interesting facts, including that the day is actually longer than 24 hours at this time of year!
In June, the day (as measured by successive returns of the midday sun) is nearly 1/4 minute longer than 24 hours. Hence, the midday sun (solar noon) comes later by the clock on the June solstice than it does one week before. Therefore, the sunrise and sunset times also come later by the clock.
In ancient times, the date of the June solstice helped people manage their calendars and decide when to plant and harvest crops. June was also a traditional month for weddings, and is to this day. Some societies invested a lot of effort to establish the length of the year. Solstice rituals and celebrations have occurred throughout history in all parts of the world, according to timeanddate.com.
Stonehenge was built around 3100 BCE. Some people believe that it was built to help establish when the summer solstice occurred. Interestingly, the sun rises at a particular point on the horizon as viewed from the centre of the stone circle on day of the June solstice. At that point the builders may have started counting the days of the year. Many other megalith structures in Europe may have been built for similar purposes, although reasons are still uncertain.
Two days from now, very early Sunday morning, we’ll see a moon that’s 30% brighter and 16% closer than a normal full moon. We’re about to experience the most “super” supermoon of 2013 on June 22-23
The moon’s orbit is egg-shaped, and there are times when it is at its shortest distance from Earth in the lunar cycle. If the full moon phase happens to fall at the same time as the shortest distance from Earth occurs, then we get a “supermoon.” This month’s full moon is the closest and largest full moon of the year, and is the moon’s closest encounter with Earth for all of 2013. The moon will not be so close again until August, 2014.