The "Chiron II" planetarium at Tamarokuto Science Center in Tokyo was certified as the "most progressive planetarium" by Guinness World Records.
The Chiron II was developed by a Kyoto-based firm, Goto Inc. And a press conference was organized at the center.
The planetarium was certified because it is for large domes and equipped with an LED light source and can display as many as 140 million fixed stars. Before the certification, a planetarium in Shizuoka Prefecture, Japan, had been the most progressive planetarium.
With 12 "fixed star plates," the Chiron II can project 140 million fixed stars including 70,000 stars of the first to eighth magnitudes as well as stars of up to the 18th magnitude that constitute the Milky Way.
"By elaborately depicting the first to 18th magnitude stars, it becomes possible to beautifully depict the dark area of the Milky Way," Goto said.
The magnitude of star is expressed by the size of a hole made in the metal film on the surface of the fixed star plate by an etching method. And the diameter of the smallest hole is several micrometers.
The Chiron II uses a high-brightness LED whose color temperature is 5,000K as its light source. The product life of the LED is more than 10 times longer than that of the metal halide lamp used in the previous model, "Chiron," enabling to drastically save maintenance effort and reduce the diameter to about 70cm (the diameter of the Chiron is about 1m).
Because LED light has a high directivity, Goto formed an optical system between the light source and the fixed star plate.
"It was difficult to obtain an even light," the company said.
The Chiron and Chiron II are the only planetariums that can display as many as 140 million stars in the world. The locations and magnitudes of the stars are based on multiple observation data collected by the US Naval Observatory, Nagoya University, etc.
The planetarium dome of Tamarokuto Science Center employed the Chiron II when it was redesigned in July 2012. Its planetarium system consists of the Chiron II, which projects stars, and four projectors that project sceneries and video for explanation. With a diameter of 27.5m, the dome is the largest in eastern Japan and the fourth largest in the world. The Chiron II will also be sold to Nagasaki Science Museum, in Nagasaki, Japan, in March 2013.