Summer will begin in the Northern Hemisphere on Friday, June 20, as the sun reaches its highest point of the year at midday. Known as the summer solstice, this astronomical milestone marks the longest day and shortest night of the year in the Northern Hemisphere (and the shortest day and longest night in the Southern Hemisphere).
The Stonehenge Monument in Maryhill, Washington, U.S.
The June solstice will occur at precisely 10:42 p.m. EDT on Friday, June 20 (Saturday, June 21 at 02:42 UTC).
The 23.5-degree tilt of the Earth's axis causes seasons. The June solstice occurs when the Earth’s axis is tilted toward the sun, meaning more sunlight for longer in the Northern Hemisphere. That causes the longest day and the shortest night.
The opposite is true for the Southern Hemisphere, which on the June solstice has its shortest day and longest night.
As a result of the solstice, regions close to the Arctic Circle experience the Midnight Sun, where the sun doesn’t set at all. In the Antarctic Circle, it's the Polar Night, where the sun does not rise.
On the date of the June solstice, the sun reaches a position directly over the Tropic of Cancer, a latitude line approximately 23.5 degrees north of the equator. The Tropic of Cancer runs through North America (Mexico and the Bahamas), Africa (Algeria, Western Sahara, Mauritania, Mali, Niger, Libya and Egypt), the Middle East (Saudi Arabia, the United Arab Emirates and Oman) and Asia (India, Bangladesh, Myanmar, China and Taiwan).
On Thursday, July 3 — just two weeks after the June solstice — Earth will be farthest from the sun in 2025. That occurs because Earth's orbit around the sun is slightly elliptical. At aphelion, Earth is 94.5 million miles (152 million kilometers) from the sun. Six months later, at perihelion, it will be 91.4 million miles (147 million kilometers) from the sun. That’s about a three percent difference. Aphelion emphasizes that it's not Earth's proximity to the sun that causes the seasons, but rather the tilt of its axis.
The most famous place to celebrate is Stonehenge in the United Kingdom, an ancient Neolithic monument thought to align with the rising sun on the date of the June solstice. English Heritage offers a YouTube livestream of the event. For something similar in North America, several Stonehenge replicas mark the solstice in various ways. In Maryhill, on the north side of the Columbia River that separates the states of Washington and Oregon, Solstice at Stonehenge will be marked with two days of celebrations at the Stonehenge Memorial Monument, which was completed in 1929 as a World War I memorial, according to the Maryhill Museum. It's aligned to the astronomical horizon rather than the actual midsummer sunrise. Beside the Guadalupe River in Ingram, Texas, the concrete Stonehenge II is open 24 hours. The Hill Country Arts Foundation owns it. Also open from dawn to dusk is Carhenge, a quirky replica near Alliance, Nebraska, that features 39 automobiles painted to resemble stones.
In New York City, Times Square will host its annual mass yoga event, Solstice in Times Square, on June 20, while Seattle will stage its Fremont Solstice Parade on June 21.