Sunspace for Shibukawa functions as an observatory in which the relative path of the sun moving across the sky can be charted over the duration of a year and is based on the sun-path studies pursued at Studio Olafur Eliasson. Visitors enter Sunspace for Shibukawa via a narrow corridor that leads into the inner space, suited for observation in solitude or in small groups. A series of circular prisms are mounted in ocular openings in the domed roof. On sunny days, visitors will experience an arc of light: the colours of the entire colour spectrum will be projected onto the inner white spherical surface through one of the prisms. Nearby prisms may create fragments of rainbows.
Approximately every second week, a perfectly round rainbow will be projected onto the convex surface directly opposite the prism through which the light is emitted. The timing of the rainbow occurrences has determined the positions of the oculi across the roof of the observatory. In winter, the rainbow will be visible in early morning, with autumn and spring affording views
later in the day. On the summer solstice, the round rainbow will appear at the latest hour in the day. The gradual temporal shifts in the occurrence of the rainbows subtly merge celestial movement
with the experience of space and light.