Anish Kapoor. Sky Mirror.

A mirror in the street

In the autumn of 2006, from 19 September to 27 October, people passing Rockefeller Center in New York met a strange object. At the Fifth Avenue entrance to the Channel Gardens stood a disc of polished stainless steel, 35 feet across, about 10.7 metres.

The disc weighed 23 tons and stood nearly three storeys tall. It sat on a platform a few feet above the street. Public Art Fund brought it there as part of its public art programme.

The work was called Sky Mirror. Its maker was Anish Kapoor, an artist born in Mumbai who lives and works in London.

The work stood right in the path of pedestrians. Morning commuters, tourists, delivery workers all had to pass it. No ticket, no gallery to enter. Anyone could stop for a few seconds and see the sky suddenly lying where it should not be.

Two faces, two cities

Sky Mirror has two faces, and each does something different.

The concave face points upward, toward 30 Rockefeller Plaza. Being concave, it turns everything it reflects upside down. The skyscraper appears head down, the sky fills most of the mirror, and clouds seem to drift below the ground.

The convex face looks out on Fifth Avenue. This side does not invert; it stretches. Passers by see themselves, the traffic, the shopfronts, all bent as if seen through a drop of water.

So one object gives two cities. One above, upside down, almost all sky. One below, curved and crowded. Walking around the disc is walking from one city to the other.

Non object

Public Art Fund cites Kapoor's term for this kind of work: a non object. A sculpture that, for all its size, suggests a window or a void and often seems to disappear into its surroundings.

It sounds contradictory. Sculpture is the art of mass, of things that take up space. Kapoor makes things that take up space in order to vanish. The steel is polished until the steel is no longer visible. Only what it reflects remains.

He had pursued the idea before. Public Art Fund mentions Turning the World Inside Out from 1995, and Cloud Gate from 2004 in Chicago's Millennium Park, a polished steel form weighing 125 tons. Other works, such as Ishi's Light, also work with reflective surfaces and the hollow within.

In Sky Mirror the idea was placed in one of the busiest districts in the world. A place where everything is tall, loud, demanding to be seen. And a large object chose to demand nothing.

Looking down to see the sky

People in Manhattan rarely look at the sky. Buildings block it, and the neck must tilt far back. Sky Mirror brought the sky down to eye level. To see clouds, one only had to look straight ahead.

The mirror changed by the hour. Blue and bright in the morning. Gold, then pink, in the evening. Grey on rainy days, with drops on the steel blurring the reflection. The work has no colour of its own. Its colour is that day's sky.

Nearly six weeks later it was taken down. Nothing it reflected was stored anywhere. That is why Sky Mirror is remembered: it kept no image; it only taught people how to look up.