Kremlin stars
Encyclopedia
The Kremlin stars are the pentagonal luminescent ruby
stars, installed in the 1930s on five towers of the Moscow Kremlin
, replacing the gilded eagles that had symbolized Imperial Russia.
two-headed eagles, installed in pre-revolutionary times, which were a part of the Coat of Arms of Imperial Russia
.
The body of each star was made of stainless steel
and covered with copper plating
. The Kremlin stars were decorated with a hammer and sickle
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 glass
, in time for the 20th anniversary of the October Revolution
. One more star was also installed on the Vodovzvodnaya tower.
), 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 prismatic
glass plates. The power of these lamps (3.7 kW
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 efficacy
of 22 lm
/W. The 5 kW lamps are 383 mm in length, the diameter of their retort
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 wavelength
of no more than 620 nm. 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-Khrustalny
glass factory. The ruby layer of the sheets is actually colored by adding colloidal gold
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.
Ruby
A ruby is a pink to blood-red colored 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 Kremlin
Moscow Kremlin
The Moscow Kremlin , 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
Copper 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 soft and malleable; an exposed surface has a reddish-orange tarnish...
two-headed eagles, installed in pre-revolutionary times, which were a part of the Coat of Arms of Imperial Russia
Coat of arms of Russia
The coat of arms of Russia have gone through three major periods in their history, undergoing major changes in the transitions between the Russian Empire, the Soviet Union, and the Russian Federation. They date back to 1472, when Ivan III began using the double-headed eagle in his seal, which,...
.
The body of each star was made of stainless steel
Stainless steel
In metallurgy, stainless steel, also known as inox steel or inox from French "inoxydable", is defined as a steel alloy with a minimum of 10.5 or 11% chromium content by mass....
and covered with copper plating
Plating
Plating is a surface covering in which 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 sickle
Hammer and sickle
The 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 glass
Cranberry glass
Cranberry glass is a red glass made by adding gold chloride to molten glass. Tin, in the form of stannous chloride, is sometimes added in tiny amounts as a reducing agent...
, in time for the 20th anniversary of the October Revolution
October Revolution
The October Revolution , also known as the Great October Socialist Revolution , Red October, the October Uprising or the Bolshevik Revolution, was a political revolution and a part of the Russian Revolution of 1917...
. 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 tonneTonne
The tonne, known as the metric ton in the US , often put pleonastically as "metric tonne" to avoid confusion with ton, is a metric system unit of mass equal to 1000 kilograms. The tonne is not an International System of Units 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 prismatic
Prism (optics)
In 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 kW
Kw
kw or KW may refer to:* Kuwait, ISO 3166-1 country code** .kw, the country code top level domain for Kuwait* Kilowatt* Self-ionization of water Kw* Cornish language's ISO 639 code* Kitchener–Waterloo, Ontario, Canada...
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 efficacy
Luminous efficacy
Luminous efficacy is a measure of how well a light source produces visible light. It is the ratio of luminous flux to power. Depending on context, the power can be either the radiant flux of the source's output, or it can be the total electric power consumed by the source.Which sense of the term is...
of 22 lm
Lumen (unit)
The lumen is the SI derived unit of luminous flux, a measure of the total "amount" of visible light emitted by a source. Luminous flux differs from power in that luminous flux measurements reflect the varying sensitivity of the human eye to different wavelengths of light, while radiant flux...
/W. The 5 kW lamps are 383 mm in length, the diameter of their retort
Retort
In 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 wavelength
Wavelength
In 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 620 nm. 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-Khrustalny
Gus-Khrustalny
Gus-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 gold
Colloidal gold
Colloidal gold 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 ....
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.