The Summer Solstice in the Northern Hemisphere occurs this year at 9:14am on June 21, 2022 (UT or Greenwich Time). The Winter Solstice in the Southern Hemisphere occurs at the same time. That will be 2;14am Pacific, 5:14am Eastern time in the USA.
This is the time that the sun will have reached it’s farthest point north in the sky for the year. At the north pole, the sun will be closest it comes to directly overhead.
Though scientifically an actual moment in time, the Solstice has been popularized as covering the whole day. It is considered the actual first day (in the north) of the summer season, despite whatever our calendars or weather is telling us.
It is also the longest (northern) span of daylight of the year. How long your daylight will last depends on your distance from the equator. The farther away from the equator, the more daylight hours you will have. The daylight at the equator doesn’t vary much from 12 hours at any time of year.
The Solstice is caused by the tilt of the Earth relative to the plane of it’s orbit. At the northern Summer Solstice, the north pole points as directly to the sun as it possibly can. At the northern Winter Solstice (around December 21) the south pole will be pointing as directly as it gets toward the sun.
Many people believe that in the north it is hot around this time of year because we are closer to the sun. In our orbit, however, the north’s Summer Solstice occurs when the Earth is farthest from the Sun. We’re just tilted toward it, which is the actual reason for the heat.
The southern hemisphere’s Summer Solstice (in December) is in the part of the Earth’s orbit when the planet is closest to the Sun.
The solstices have been important to many cultures around the world for tens of thousands of years. Astronomical calendars have been found all over the world that use the solstices as an important point in time.
For some cultures it might have meant time to plant, or time to start storing food for winter, or some other thing. But if tracked, the time the sun changes direction from moving northward to moving southward is a relatively easy marker to notice.