While the Light Hesitates

Uniquely in 2026, our visitors can experience a spectacular light installation atop the Round Tower. “While the Light Hesitates”, created by the design studio Yoke, launches the program Light Year 2026 and invites both tower visitors and passers-by to sense the nature of light through scale, space and time.

A central element of astronomer Ole Rømer’s discovery of the speed of light – which the Round Tower marks the 350th anniversary of this year – is his observation of Jupiter’s innermost moon, Io. Drawing on Rømer’s observations of Io, the work unfolds the nature of light in three acts through scale, space and time. As darkness falls, the hesitation of light is transformed into circular light formations that recall the moment when light reveals its speed. The immersive experience is supported by a soundscape.

“While the Light Hesitates” is activated after dark and can be experienced atop the tower and from the surrounding city for a limited time period – an exceptional opportunity to see the Round Tower’s iconic platform with new eyes. Normally, as little light as possible is used at the top of the tower, as it would disturb the view from the Observatory; however, as the Observatory is being restored in 2026, this presents a rare chance to experience light art and science hand in hand nearly 35 meters above Copenhagen.

Yoke brings together technology, space and storytelling in sensory and interactive works that explore how we experience and understand the world. As storytellers, designers, creative technologists, and makers, they work at the intersection of art, design, and communication – driven by curiosity and a desire to turn knowledge into experience.

The light installation is part of the program for Light Year 2026 – a full year dedicated to celebrating light and the 350th anniversary of Ole Rømer’s groundbreaking discovery of the speed of light.

The work can also be experienced as part of the annual Copenhagen Light Festival.