10 Facts about the First Day of Summer

Finally, it’s summer!

1. It's both Summer & Winter Solstice
In the Northern Hemisphere, where it is the longest day of the year in terms of daylight, the June Solstice is also called the Summer Solstice. In the Southern Hemisphere, on the other hand, it is the shortest day of the year and is known as the Winter Solstice.

2. It's the First Solstice of the Year
Solstices happen twice a year - in June and December. The June Solstice happens around June 21, when the Sun is directly overhead the Tropic of Cancer. The December Solstice takes place around December 21. On this day, the Sun is precisely over the Tropic of Capricorn.

3. The Sun Seems to Stand Still
Solstice comes from the Latin words sol, meaning 'Sun' and sistere, meaning 'to come to a stop or stand still'. On the day of the June Solstice, the Sun reaches its northern-most position, as seen from the Earth. At that moment, its zenith does not move north or south as during most other days of the year, but it stands still at the Tropic of Cancer. It then reverses its direction and starts moving south again.

4. It Occurs at the Same Time...
June Solstice is the exact instant of time when the Sun is directly overhead the Tropic of Cancer. In 2016, this will happen on June 20 at 22:35 UTC. Because of time zones differences, the event will take place on June 21 at locations that are more than one and a half hours ahead of UTC. That includes all of Europe, Russia and Asia.

5. It Can be on June 20, 21 or 22
Even though most people consider June 21 as the date of the June Solstice, it can happen anytime between June 20 and June 22. June 22 Solstices are rare - the last June 22 Solstice in UTC time took place in 1975 and there won't be another one until 2203.

6. It's the First Day of Summer...
...depending on whom you ask. Astronomers and scientists use the date of the June Solstice to mark the beginning of summer in the Northern Hemisphere and winter in the Southern Hemisphere. For meteorologists on the other hand, summer began almost three weeks ago, on June 1.
In many Northern Hemisphere cultures, the day is traditionally considered to be the mid-point of the summer season. Midsummer celebrations on or around the Northern Summer Solstice are common in many European countries.

7. The Earth is Farthest from the Sun
One might think that since it is summer in the Northern Hemisphere, the Earth is closest to the Sun during the June Solstice. But it's the opposite - the Earth is actually farthest from the Sun during this time of the year. In fact, the Earth will be on its Aphelion a few weeks after the June Solstice.

8. The Earliest Sunrise of the Year Doesn't Happen on This Day
Even though the June Solstice is the longest day of the year in the Northern Hemisphere, most places do not see the earliest sunrise of the year on this day. The earliest sunrise happens a few days before and the latest sunset takes place a few days after the June Solstice.

9. Not Usually the Hottest Day of the Year
In fact, the hottest day of the year in the Northern Hemisphere usually comes a few weeks or sometimes months after the Solstice. This is because it takes time for the oceans and landmasses to warm up, which again allows for higher air temperatures. This phenomenon is called the delay or lag of the seasons.

10. The Arctic Circle has 24 Hours of Daylight
The June Solstice is the only day of the year when all locations inside the Arctic Circle experience a continuous period of daylight for 24 hours. Due to atmospheric refraction, however, the Midnight Sun is visible for a few days before and on the June Solstice from areas as far as 60 miles (97 kilometers) south of the Arctic Circle. As one moves further north of the Arctic Circle, the number of days with the Midnight Sun increase.

CREDIT: http://www.timeanddate.com/astronomy/facts-about-june-solstice.html