The
Kremlin stars are the pentagonal luminescent
rubyA ruby is a pink to blood-red gemstone, a variety of the mineral corundum . The red color is caused mainly by the presence of the element chromium. Its name comes from ruber, Latin for red. Other varieties of gem-quality corundum are called sapphires...
stars, installed in the 1930s on five towers of the
Moscow KremlinThe Moscow Kremlin otherwise known as the Russian Parliament , sometimes referred to as simply The Kremlin, is a historic fortified complex at the heart of Moscow, overlooking the Moskva River , Saint Basil's Cathedral and Red Square and the Alexander Garden...
, replacing the gilded eagles that had symbolized Imperial Russia.
The first Kremlin star was installed on top of the Spasskaya Tower on October 25, 1935. During the next week, another three stars were installed on the Troitskaya, Nikolskaya and Borovitskaya towers.
The
Kremlin stars are the pentagonal luminescent
rubyA ruby is a pink to blood-red gemstone, a variety of the mineral corundum . The red color is caused mainly by the presence of the element chromium. Its name comes from ruber, Latin for red. Other varieties of gem-quality corundum are called sapphires...
stars, installed in the 1930s on five towers of the
Moscow KremlinThe Moscow Kremlin otherwise known as the Russian Parliament , sometimes referred to as simply The Kremlin, is a historic fortified complex at the heart of Moscow, overlooking the Moskva River , Saint Basil's Cathedral and Red Square and the Alexander Garden...
, replacing the gilded eagles that had symbolized Imperial Russia.
Installation
The first Kremlin star was installed on top of the Spasskaya Tower on October 25, 1935. During the next week, another three stars were installed on the Troitskaya, Nikolskaya and Borovitskaya towers. These stars replaced the huge
copperCopper is a chemical element with the symbol Cu and atomic number 29.It is a ductile metal with very high thermal and electrical conductivity. Pure copper is rather soft and malleable and a freshly-exposed surface has a pinkish or peachy color...
two-headed eagles, installed in pre-revolutionary times, which were a part of the
Coat of Arms of Imperial RussiaThe coat of arms of the Russian Federation derives from the earlier arms of the Russian Empire, as restored in 1992 after the dissolution of the Soviet Union. Though modified more than once since the reign of Ivan III , the current coat of arms is directly derived its mediaeval original. The...
.
The body of each star was made of
stainless steelIn metallurgy, stainless steel, also known as inox steel or inox, is defined as a steel alloy with a minimum of 11% chromium content by mass. Stainless steel does not stain, corrode, or rust as easily as ordinary steel...
and covered with copper
platingPlating describes surface-covering where a metal is deposited on a conductive surface. Plating has been done for hundreds of years, but it is also critical for modern technology...
. The Kremlin stars were decorated with a
hammer and sickleThe hammer and sickle is a part of communist symbolism and its usage indicates an association with Communism, a Communist party, or a Communist state. It features a hammer and a sickle overlapping each other. The two tools are symbols of the industrial proletariat and the peasantry; placing them...
on both sides, made of semi-precious stones from the Ural mountains. The installation of the first Kremlin stars did not meet the designer's expectations since the surfaces of the semi-precious stones lost their luster and required re-faceting. In 1937, these stars were replaced with new ones made of
ruby glassCranberry glass is a red glass made by adding gold chloride to molten glass. Tin, in the form of stannic chloride, is sometimes added in tiny amounts as a reducing agent...
, in time for the 20th anniversary of the
October RevolutionTheOctober Revolution , also known as the Soviet Revolution or Bolshevik Revolution, was a political revolution and a part of the Russian Revolution. It began with an armed insurrection in Petrograd traditionally dated to 25 October 1917 Julian calendar...
. One more star was also installed on the Vodovzvodnaya tower.
Characteristics of the stars
The size and the form of each of the five stars were defined proceeding from the height and architectural features of each corresponding tower. The distance between the end points of beams of the star installed on the Vodovzvodnaya tower equals 3 m, Borovitskaya tower – 3.2 m, Troitskaya tower – 3.5 m, Nikolskaya and Spasskaya towers – 3.75 m. The bearing construction of each of the Kremlin stars is made of stainless steel and represents a spatial pentagonal star, the points of which have the form of a tetrahedral pyramid. The durability and rigidness of the construction was designed to withstand the maximum pressure of a hurricane wind equaling 200 kgf per square meter (2 kPa). Despite the considerable mass of each star (approx. 1
tonneA tonne or metric ton , also referred to as a metric tonne, is a measurement of mass equal to , or approximately the mass of one cubic metre of water. It is not an SI unit but is accepted for use with the SI...
), they revolve pretty easily as the wind changes its direction. Because of its form, each star always positions itself with its frontal side against the wind. The Kremlin stars are illuminated from the inside by filament lamps so that they could be seen against the sky. Even distribution of light inside the stars is ensured by the refractors, which consist of
prismaticIn optics, a prism is a transparent optical element with flat, polished surfaces that refract light. The exact angles between the surfaces depend on the application. The traditional geometrical shape is that of a triangular prism with a triangular base and rectangular sides, and in colloquial use...
glass plates. The power of these lamps (3.7
kWkw or KW may refer to:* Kuwait* kW, kilowatt* Kw, the self-ionization of water* kw, the Cornish language * KW, Kitchener-Waterloo, Ontario, Canada* KW, Kripke's Wittgenstein in Kripkenstein* Kanye West a rapper...
in the stars of the Vodovzvodnaya and Borovitskaya towers and 5 kW in the remaining three) ensures good visibility of the stars day and night. The lamps have a
luminous efficacyLuminous efficacy is a figure of merit for light sources. It is the ratio of luminous flux to power . As most commonly used, it is the ratio of luminous flux emitted from a light source to the electric power consumed by the source, and thus describes how well the source provides visible light...
of 22
lmThe lumen is the SI unit of luminous flux, a measure of the perceived power of light. Luminous flux differs from radiant flux, the measure of the total power of light emitted, in that luminous flux is adjusted to reflect the varying sensitivity of the human eye to different wavelengths of light...
/W. The 5 kW lamps are 383 mm in length, the diameter of their
retortIn a chemistry laboratory, a retort is a glassware device used for distillation or dry distillation of substances. It consists of a spherical vessel with a long downward-pointing neck. The liquid to be distilled is placed in the vessel and heated...
s is 177 mm. Each lamp produces a lot of heat, thence, each star has to be cooled off every now and then. For this purpose, each tower is equipped with two fans aimed at the star.
When the stars were being covered with glass, the experts had to take into consideration the fact that the stars had to shine brightly during the night and keep their ruby red color during the day, so that the electrical filament in the lamps remained invisible. Also, the experts had to consider the fact that the red glass illuminated from the outside by the sun appears almost black. In 1946, they installed a combination of different types of glass for the stars, namely, ruby red and milk-white glass with a layer of transparent crystal glass between them. The milk-white glass disperses the light of the lamps and reflects most of the daytime light at the same time, softening the darkness of the ruby glass during the day. In order to achieve more contrast and emphasize the beams of the stars, they installed the ruby glass of different shades, which absorbs only the red rays with a
wavelengthIn physics, the wavelength of a sinusoidal wave is the spatial period of the wave – the distance over which the wave's shape repeats.It is usually determined by considering the distance between consecutive corresponding points of the same phase, such as crests, troughs, or zero crossings, and is a...
of no more than 0.62 µm. The thickness of glass in the stars is 6-8 mm. The area of a star covered with glass equals 6 m². The special three-layered glass sheets (milky white, crystal clear and ruby) were manufactured by
Gus-KhrustalnyGus-Khrustalny is a town in Vladimir Oblast, Russia, located on the Gus River south of Vladimir. Population: 65,000 ; 40,000 ; 17,900 ....
glass factory. The ruby layer of the sheets is actually colored by adding
colloidal goldColloidal gold, also known as "nanogold", is a suspension of sub-micrometre-sized particles of gold in a fluid — usually water. The liquid is usually either an intense red colour , or a dirty yellowish colour . The nanoparticles themselves can come in a variety of shapes...
to the glass.
The machinery that services the Kremlin stars is located inside the towers. Special lifting devices allow for the periodic cleaning of the stars inside and out, removing dust and soot. The machines replace burnt-out lamps within 30-35 min. Experts in a special control room observe the work of the machinery.