June 20, 2020, is the astronomical start of summer in the Northern Hemisphere (Credit: manorhousebuilders.com)

With the days getting increasingly longer and warmer, the Northern Hemisphere summer may seem to be well on its way. However, though the meteorological season, which evenly splits the 12 months of the year into four seasons, started on June 1, 2020, the astronomical summer will not begin until June 20, 2020. Called summer solstice, it is the day when the North Pole is most inclined towards the Sun, allowing residents of the Northern Hemisphere to enjoy the longest day (and shortest night) of the year. Conversely, Southern Hemisphere residents will celebrate the astronomical start of winter, or winter solstice, with the shortest day (and longest night) of 2020.

Though the celebrations extend throughout the day, the solstice technically occurs at a single point in time — when the Sun is right over the Tropic of Cancer, its farthest northerly position in the sky. In 2020, this will occur at 5:43 pm ET (2:43 pm PT). Interestingly, the longest day of the year does not coincide with the earliest sunrise or latest sunset of the year. Those will take place a week before and a week after the solstice, respectively. The mismatch is due to our planet's elliptical orbit, which causes it to travel at different speeds – fastest when it's closest to the Sun and slowest when farthest away, as is the case in the summer. Earth's velocity around its axis, on the other hand, remains constant throughout the year. The difference between our planet's orbital motion and its own rotation determines the exact sunrise and sunset times.

The Northern Hemisphere summer solstice occurs when the Sun is at its farthest northerly point in the sky (Credit: Farmersalmanac.com)

While all countries north of the equator will enjoy at least 12 hours of daylight, many will get much more. The residents of the beautiful city of San Francisco, CA, will bask in over 14 hours of sunshine, while the folks in London, UK, will enjoy just over 18 hours. The Swedish city of Stockholm will experience 21 hours of light and some areas of the Arctic Circle will have a full 24 hours!

The summer solstice is usually observed with numerous public events worldwide. One of the oldest and most revered celebrations takes place at Stonehenge in Wiltshire, England. Though its exact purpose is a mystery, the Neolithic stone circle — built in three phases between 3000 BC and 1600 BC — is designed to align with the midsummer sunrise and midwinter sunset. Thousands of visitors from around the world gather at the historic site every year to witness the magical sight of the Sun rising above the stones. Unfortunately, due to the COVID-19 pandemic restrictions on large gatherings, visitors will not be able to access the site this year. To make up for the disappointment, Stonehenge officials will live stream the summer solstice sunrise and sunset on social media sites such as Facebook.

Observing the sunrise at Stonehenge is a popular summer solstice tradition (Credit: Andrew Dunn/ CC-BY-SA- 2.0/Wikipedia Commons)

Stonehenge director Nichola Tasker said, "We hope that our live stream offers an alternative opportunity for people near and far to connect with this spiritual place at such a special time of year, and we look forward to welcoming everyone back next year."

The coastal city of Santa Barbara, CA, which usually hosts a three-day summer solstice celebration with elaborate parades, is also taking this year's festival online. The two-day event, which starts on June 19, 2020, features a host of fun festivities, including solstice-related films and documentaries, interviews with special guests, a virtual dance party, and even a virtual parade! If you know of any other online summer solstice activities, be sure to share it with us by adding your comments below.

Resources: abcactionnews.com, newminer.com, wikipedia.com