Officially called the Twins but known locally as the “Orbs”, the structures were commissioned during Churchill Square’s redevelopment between 1996 and 1998.
Wear and tear saw them removed in August last year for refurbishment – but now they have been reinstalled ahead of the busy Christmas period.
Brighton artist Charlie Hooker, who designed the sculptures, said: “I actually think they are more beautiful than before.”
A panel of arts advisers and Standard Life representatives awarded the commission to Mr Hooker in 1996 after a competition to find a landmark for the revamped centre.
The former professor of sculpture at the University of Brighton spent almost two years designing and building the installation with a team of assistants.
Three decades on, the sculpture has been refurbished with modern technology while preserving its environmental message.
Charlie Hooker, 72 (Image: NQ staff)
Mr Hooker, who lives in Uckfield, said climate science and the natural forces shaping everyday life inspired the artwork.
He said: “At the time I was working closely with scientists and helping communicate scientific ideas to the public.”
The artwork uses sound, light and sculpture to reflect the changing seasons.
The installation is split into two halves, with autumn and winter on one side and spring and summer on the other. Its 12 sections represent the months of the year.
Mr Hooker composed a piece of music for each month, creating a changing soundscape driven by sunlight.
The work was inspired by a meteorological instrument called a sunshine recorder.
The device focuses sunlight through a glass sphere on to a card, burning a visible track when the sun shines.
Hooker installed a sunshine recorder on Churchill Square’s roof in 1997, recording the sun’s track at the start and end of each month.
The patterns were converted into music using audio software, then etched permanently into the sculpture’s bronze panels.
The resulting compositions range from what Hooker describes as “hot, lively sounds” in spring and summer to “cold, stormy sounds” during autumn and winter.
When sunlight hits the sculpture’s sensors, its music grows louder and richer.
On cloudy days, the music softens; at night, it fades completely.
At dusk, energy stored during the day powers lights that project two six-pointed stars across the piazza floor.
From a distance, the illuminated sculptures look like two glowing forms joined by light.
Hooker, 73, said: “I wanted something that changed every day and throughout the year.”
Each granite plinth doubles as a seat, allowing visitors to lean back against the sculptures and hear the changing soundscape.
Professor Charlie Hooker stood outside the statues as they are rebuilt (Image: NQ staff)
After three decades of public use, the artwork’s original electronics and lighting had begun to fail.
Mr Hooker said members of the public had repeatedly contacted him to ask why parts of the installation no longer worked properly.
Ikea’s parent company, which owns Churchill Square, approached him to bring the sculptures back to life.
Sheffield-based audio-visual specialists AVAC Ltd carried out the work, having also created the original electronics in the late 1990s.
The new version includes Bluetooth-controlled systems, upgraded lighting and more energy-efficient technology.
The restoration retained the original bronze, granite, steel and glass, recycling the materials into the upgraded work.
Several cracked granite panels were repaired using kintsugi, the Japanese technique of highlighting damage with gold rather than hiding it.
Mr Hooker said: “The whole philosophy is to show the history and value the history of something.”
The artist closely supervised the restoration, regularly visiting the factory to oversee the installation’s look, sound and character.
For Mr Hooker, who left school at 15 before studying at Brighton Polytechnic, the project means more than preserving public art.
Mr Hooker said: “We’re all linked into that system of climate and we have to take care of it.
“What I try to do is help people see how precious the balance of nature is.”
As the Twins return to Churchill Square, Hooker hopes its message remains as relevant as ever.
He said: “Twins is fundamentally about the environment and climate science.
“It invites us to think about the natural balance that powers our planet and the importance of maintaining it.”
With renewed sound, light and solar-powered technology, the sculptures look set to tell that story for years to come.