December 22 is the shortest day of the year in the northern year. Moscow, for example, has less than six hours of daylight. The day marks the beginning of astronomical winter in the northern hemisphere, and a public holiday for those who provide Russia wi

Winter has finally arrived! Even though for most of us it's already started, astronomers have only just begun to tick off winter days.

The northern hemisphere has just had its longest night of the year, with Moscow experiencing more than 18 hours of darkness.

This happens when the sun moves to the opposite side of the equatorial plane. And for the unlucky inhabitants of the northern part of the world it stays above the equator for just a very short time.

For some of Russia's population the light leaves for months giving way to polar night. The shortest day of the year normally goes unnoticed there – after all people have long been used to little sunlight.

But in China, it's thought to bring luck and is marked with dancing and fireworks.

The only people in Russia for whom this day is special are those working in the power industry.

On December 22, more than half-a-million of them who switch on the lights in the country celebrate their professional holiday.

From now on, days will start to grow longer, and in the meantime astronomers say there's a lot to watch out for during the long night hours.

St. Petersburg to greet longest night with light show 

Light show at Mikhailovsky Palace

In St. Petersburg, the long nights are being illuminated by a special show staged at one of the city’s most famous landmarks.

Several groups have joined up for a performance using the Mikhailovsky Palace as a backdrop.

The neo-classical palace, now the Russian Museum, was built in the first half of the nineteenth century.