By Environment Correspondent Alister Doyle

RJUKAN, Norway (Reuters) - Sunshine lit up a Norwegian town in a remote, dark valley for the first time in wintertime on Wednesday, as mirrors high on a mountainside realized a century-old dream.

About 1,000 people, including children wearing sunglasses and with yellow suns painted on their faces, cheered when the sun broke through clouds to illuminate the main square in Rjukan, until now in shadow from early October to mid-March.

"It's a crazy idea - but a bit of madness is fun," said Oystein Haugan, who led the 5 million crown ($849,300) project to set up the three mirrors with a combined surface area of 51 sq meters (550 sq ft) that will track the sun by computer.

"We hope this will bring joy to people here," he said of the 3,500 inhabitants of the industrial town about 175 kms (110 miles) west of Oslo.

A band played the 1960s hit "Let the Sunshine In", several women lounged on sunbeds drinking cocktails - fully dressed against temperatures of 7 degrees Celsius (45 Fahrenheit) - and a volleyball court was set up on a pile of sand.

The reflected sunlight, covering 600 sq meters (6,500 sq ft), is meant to create a meeting place for sun-starved locals and a draw for tourists. Organizers reckon the reflected light will be about 80 percent as bright as the real sun.

The sun shines here in the summertime, when it's higher in the sky, but sets on October 4 behind the mountain and does not return until March 12.

Similar mirrors were first set up in 2006 in the Italian village of Viganella in the Alps, which is also hemmed in a dark valley. "It was a great satisfaction and everyone was happy about it," local mayor Pier Franco Midali told Reuters by e-mail.

BRIGHT IDEA

Steinar Bergsland, mayor of the area including Rjukan, said he hoped the mirrors would attract visitors. "And people get happy from seeing the sun," he said.

Rjukan nestles in a deep valley in the shadow of Gaustatoppen, a 1,883-metre high mountain that hosts a ski resort. The mirrors are on a ridge at 742 meters, about 450 meters above the town center.

The idea was first proposed in a letter to a local newspaper by a bookkeeper, Oscar Kittilsen, on October 31, 1913. Organizers brought forward the planned unveiling of the mirrors from the anniversary on Thursday because rain is forecast.

A few people in Rjukan are against the mirrors, reckoning they are an expensive gimmick.

"I am resigned to them now," said Jan Hagalia, 63, a carpenter who was among the most vocal opponents. "It costs a lot. And the mirrors will have to be maintained, cleaned. That will mean a lot of expensive helicopter trips."

But almost all the locals are in favor.

"It's a fun stunt," said Maryan Listaul, 43, who runs a local flower shop with a sign outside saying "Hurray for the sun mirror". She added: "I don't think it will be any warmer."

($1 = 5.8871 Norwegian krones)

(Reporting By Alister Doyle; editing by Barry Moody)