What is the summer solstice and why is it the longest day of the year?

Our planet does not spin on a perfectly vertical axis — it is tilted.

This tilt causes the amount of sunlight that reaches different regions of Earth to change throughout the year as it orbits the Sun.

For half the year the northern half of the Earth is tilted toward the Sun.

On the summer solstice the northern hemisphere is tilted most directly toward the Sun, and the Sun appears directly overhead at the Tropic of Cancer.

Without this tilt we would still experience weather but not distinct seasons, as the amount of daylight would remain nearly constant throughout the year.

The word solstice comes from the Latin words sol (sun) and sistere (to stand still), referring to the apparent pause in the Sun's movement across the sky.

Despite being the longest day of the year, the summer solstice does not have the latest sunset or the earliest sunrise.

The earliest sunrises happen before the summer solstice and the latest sunsets happen after.

You can check sunrise and sunset times where you are on the BBC Weather app and website.