Solstice weekend

The Earth is tilted on its axis as it orbits the sun. Without the tilt, although we'd get weather, we wouldn't get seasons.

The hemisphere that is tilted towards the sun has summer and the hemisphere away from the sun has winter. The solstice is the moment in time when one hemisphere of the world has reached the point tilted most towards the sun and the other is tilted furthest away.

Once this moment has passed, the Earth begins its six-month journey towards the next solstice, bringing the opposite season to the northern and southern hemispheres.

While it's the winter solstice in one hemisphere it's the summer solstice in the other hemisphere. In the United Kingdom the solstice is a little after 11pm on 21 December this year; however all time zones east of the GMT, it is already 22 December, so the date of the solstice depends on where you are on the planet.

John Hammond explains more.