Danish-born artist Olafur Eliasson has turned Tate Modern's vast Turbine Hall into an atmospheric, foggy sunset with the aid of mist and mirrors.
The five-month exhibition, which opens on Thursday, is based on the British obsession with the weather.
Eliasson put 300 mirrors on the ceiling, and placed more than 200 lamps behind a semi-circular screen.
The "sun" appears whole thanks to the reflection, bathed in an eerie fog of frozen water vapour.
Eliasson's installation at the central London gallery took just three weeks to install, but it also took months of planning.
"Britons think they are the only ones who talk about the weather, but it is a northern hemisphere thing," he said.
"The weather has a couple of qualities I like a lot. It somehow defines a sense of community but we have very different opinions about it. I might like the rain a lot but you may dislike it."
He added: "The other thing I like is the idea of it being unpredictable. It gives off a specific sense of time. You never have the same cloud again."
Eliasson (right) met Danish Crown Prince Frederick at the launch
Eliasson said he considered freezing the whole hall, a remnant of the building's previous life as a power station.
But "it would have been winter and freezing outside, and people would have been walking in and not noticing," he said.
The fog is created by a mix of sugar and water to create the desired effect.
Eliasson is the fourth artist to have been commissioned to create a display for the hall.
Other works have included towering sculptures by Louise Bourgeois, a false floor cutting the hall in half by the late Juan Munoz and Anish Kapoor's 550ft long bright red Marsyas, which were said to resemble a pair of enormous PVC ear trumpets.
The Unilever Series: Olafur Eliasson, The Weather Project will be open to the public until March.