Why has China sent a spacecraft to the far side of the moon?
A Chinese spacecraft has landed on the far side of the moon in a landmark achievement for the nation and space exploration.
But what is the purpose of the mission and why has China decided to take this leap into the unknown?
Why all the fuss?
This is the first time any nation has landed a spacecraft on the far side of the moon.
The moon's far side isn't always dark but is sometimes called that because it faces away from Earth and is relatively unknown.
The tidal "lock" means the moon rotates on its axis at the same rate as it orbits Earth, which is why we never see the far side, which has a different composition to the near side.
What is the purpose of the mission?
Chang’e 4 - a name derived from a Chinese goddess who, according to legend, has lived on the moon for millennia - landed on the so-called 'dark side' of the moon on December 3.
A combined lander and rover, it will make astronomical observations and probe the structure and mineral composition of the terrain above and below the surface.
The probe also took six live species - cotton, rapeseed, potato, arabidopsis, fruit fly and yeast - to the moon to form a mini biosphere.
It touched down on the floor of the Von Kármán crater within the South Pole-Aitken (SPA) basin, the moon’s largest, deepest and oldest impact structure.
Chang’e 4 will hope to shed some light on the history of the basin, according to Dr Long Xiao from the China University of Geosciences.
In an article in September for the Planetary Society, he wrote: "The science team hopes to study the existence and extent of variations in composition of the sheet of melted rock that would have filled the newly formed SPA basin, and we hope to possibly study exposed upper-mantle materials.
"Scientists also expect to improve understanding of the far side space environment and the evolution of far side regolith, the broken-up rocks and dust that make the lunar surface."
What else is in it for China?
The landing was a major scientific milestone, but just as significantly it highlighted China's growing ambition as a space power.
Along with the United States and the former Soviet Union, China has previously sent missions to the near side of the moon.
But Thursday's landing was hailed as the moment China "raced to the front" of the space race.
China has plans to one day send a manned mission to the moon - only the US has done this before - and probe landings on Mars, Jupiter and asteroids are in its sights.
China also wants to have a space station in operation by the early 2020s, with construction due to begin next year.
Wu Weiren, the chief designer of the China Lunar Exploration Project, said the moon landing was a trailblazing milestone.
"Building a space power is a dream that we persistently pursue," he said in an interview with CCTV in Beijing. "And we're gradually realising it."
China insists its ambitions are peaceful, but the US has previously accused it of pursuing goals which would give China control over space assets in a future crisis.
How will we know what Chang’e 4 has found?
One challenge of operating on the far side of the moon is communicating with Earth.
To get around this, China launched a relay satellite in May so that Chang'e 4 can send back information.
The satellite, named Queqiao, is positioned so it is visible to both Chang'e 4 and the team back on Earth, allowing the transfer data and images.