Rare Solstice Annular Solar Eclipse.

In 2020, many locations will see a rare solstice annular solar eclipse on the same day as the June solstice. This will happen only twice this century, in 2020 and on June 21, 2039. If you can't see this eclipse from your city, don't despair. We will be webcasting a live hosted stream of the eclipse with lots of information, images, and facts about this and other eclipses.

Forum : International Day of the Celebration of the Solstice 2020.

When is the summer solstice? The science behind solstices and equinoxes.

When is the summer solstice 2020?

In 2020 the summer solstic will occur on Saturday 20 June 2020 at 21:43 GMT (22:43 BST). As the solstice is independent of the specific rotation of the Earth, it can occur even during the middle of the night, as it will this year.

What is the summer solstice?

The summer solstice is often referred to as the longest day of the year. On this day, the number of hours of daylight are at their maximum, while the number of hours of night are at their minimum. However, while most people consider the summer solstice to be a day, it is in reality an exact moment in time that falls upon that day.

The summer solstice occurs in June in the Northern Hemisphere and marks midsummer: the longest day and shortest night.

What is a solstice?

Our Earth rotates on its axis once each day, producing the cycle of day and night.

At the same time, the Earth moves around the Sun on its orbit over the course of a year. However, the axis of rotation of the Earth is not lined up with the axis of motion around the Sun. Instead, it is tilted slightly at 23.44°. This is sometimes referred to as the 'ecliptic'.

This tilt means that during one half of the year the North side of the Earth is tilted slightly towards the Sun and the South is tilted away. For the other half of the year the reverse is true.

At the exact moment that the northern hemisphere is most tilted towards the Sun, the northern hemisphere experiences its summer solstice while the southern hemisphere has its winter solstice. About six months later, the northern hemisphere has its winter solstice while the southern hemisphere is at its summer solstice.

These key points in the year, along with the equinoxes, help to determine the seasons on Earth.