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Time to Reflect

The Sky Mirror, an artistic creation of Anish Kapoor, resides at Rockefeller Center on fifth Avenue in New York. It is a copy of a similar piece by Kapoor that stands outside the Wellington Circus Theater in Nottingham, England.

The mirror is a 35 feet in diameter concave mirror made of polished stainless steel. With its base, it weighs 23 tons.

To observers on the street (and in nearby buildings), the Sky Mirror "literally brings the sky down to the ground....Its concave side, angled upward, faces 30 Rockefeller Plaza, reflecting an upside-down portrait of this elegant and iconic New York City skyscraper and the shifting sky around it. Its convex side, facing Fifth Avenue reflects a more earthly vision: viewers in the midst of the adjacent streetscape. This optical object changes through the day and night and .... suggests a window or void and often seems to vanish into its surroundings."

Your Task to "Reflect" On: Suppose that the mirror, when laid flat on the ground with convex side up, has a distance of 3 feet fom the the highest point of the arched mirror to the ground. It is possible to view this mirror as a section of a "parent" sphere. Can you find the following:

  • The radius of the "Parent" sphere?
  • The percent of surface area represented by the mirror, relative to the "parent" sphere?
  • The weight of the "parent" sphere?

Unfortunately, the Sky Mirror was a temporary exhibit....and it will now go to the highest bidder. The starting asking price is $5 million.

Source: New York Times, October 13, 2006