When Does Summer 2017 Start? Summer Solstice to Arrive on June 21
Those looking forward to feeling this year's summer heat might be happy to know that the summer solstice is just a few months away. And for 2017, the summer solstice in the northern hemisphere is scheduled to take place on Wednesday, June 21.
The summer solstice is the "longest" day of the year and also marks the middle of summer. This is the time of year the tilt of the Earth's axis is most aligned with the sun, providing the planet with the most daylight of the year.
After the day of the summer solstice, the nights will slowly begin to get longer as the planet rotates away from the sun. The day the Earth is located furthest from the sun is called the winter solstice.
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How is the date of the summer solstice established? Well, for those who are interested to know the process of deciding the day of the summer solstice, the midsummer date is actually set based on the Earth's rotational axis.
This means the date of the summer solstice is dependent on the sun's tilt towards the sun, which reaches its maximum at 23° 26′ and falls between the dates June 20 and June 22 in the northern hemisphere.
The summer solstice in the northern hemisphere doesn't fall on the same date each year partly because of the difference between the Gregorian calendar system — which usually has 365 days — and the tropical year — the actual duration it takes for Earth to orbit the sun once — which is about 365.242199 days.
In order to compensate for the missing fraction of days, the Gregorian calendar adds a leap day around every 4 years, which makes the date of the summer solstice jump backward. The date also changes because of other factors, which include the gravitational pull from the Moon and other planets, and the slight wobble in the rotation of planet Earth.
Aside from being the longest day of the year, the summer solstice also marks the start of midsummer festivities which are held all over the world in many different cultures.
