Tesla's plasma ball and Foucault's pendulum. Chief exhibits of the Moscow Planetarium

November 15

Opened in 1929 to be the first in Russia and the thirteenth in the world, the Moscow Planetarium celebrated its anniversary in early November. Since its launch, the Planetarium has been functioning as an educational and science promoting facility. Started 90 years ago, these activities still continue.

Today, Planetarium is a large complex including the Urania Museum and the interactive Lunarium, the Great and Small Star Halls, the Sky Park and the Observatory. It stores functioning historical scientific instruments related not only to astronomy. They help studying human thought development, and Universe and Earth laws. Read about the most outstanding exhibits of the star house in the mos.ru and Mosgortur Agency's collaborative article.

 Galileo Galilei and Isaac Newton's telescopes 

We do not know who invented a telescope, even the date of its invention is only approximate — the early 17th century. In 1608, Dutch spectacle-maker Johann Lippershey presented  'a spyglass' enabling to see distant objects. But he failed to get a patent, as it turned out that his compatriots Zacharias Janssen and Jacob Metius had already invented similar spyglasses a few years earlier.  Besides, drawings of primitive one or two-lens telescopes were found in Leonardo da Vinci's records made a hundred years ago. The Renaissance genius supposed that such device could make it possible to see the Moon.

In practice, Galileo Galilei was the first to look up at the starry sky through an optical device. In 1609, he made his own version of an optical tube with threefold magnification. The tube had two lenses, one  absorbing and the other diffracting light. Over time, the great Italian scientist developed a meter-long telescope with 32-fold magnification, but it significantly distorted the colours. In 1611, Greek mathematician Ioannis Dimisianos named Galileo's invention a 'telescope'.

Isaac Newton came up with an improved system of reflecting mirror telescopes. At the end of 1668, the British physicist built the first device with a concave mirror as the main light-absorbing element. Newton's telescope worked as follows: the light, entering the tube on the main mirror, was directed to a flat diagonal mirror, located near the focus to go further beyond the tube. One could see the resulting image through an eyepiece and even take its photo. Correctly transmitting colour, Newton's reflector was much lighter than Galileo's device and could reflect ultraviolet rays.

Urania Museum displays small Newton's reflecting telescope, a Galileo telescope's replica, and many up-to-date telescopes.

Another model of Planetarium and Universarium M9 

The first model of Planetarium device, designed by engineer Walther Bauersfeld, was produced in Germany in the early 1920s, at Carl Zeiss plant. Small devices projected onto the domed screen some number of stars and constellations, planets, nebulae, and the Sun and Moon. Later, larger devices added to the list of celestial objects — additional projectors showed the Milky Way, demonstrated sunrises and sunsets, and even screened films. Planetarium served as a universal device for showing the starry sky. In 1929, the Moscow Planetarium was the 13th in the world with Model II of this device installed.

After the overhaul of 2011, the Planetarium got its Universarium M9.  Today, there is a ball consisting of two hemispheres in the Grand Star Hall to screen full-dome films. Universarium hemispheres project stars, constellations and nebulae one can see with the naked eye. Advanced technologies allow to view more than 9,000 stars appearing on the dome screen. Universarium projectors  accurately recreate the starry sky, lunar and solar eclipses, comet flights and meteor showers.

Jan Heweliusz's globe 

The globe of the Polish astronomer and telescope designer of the 17th century Jan Heweliusz is one of the most renowned celestial globes, representing a map of the starry sky. Published after his death, his most popular work, 'Uranography', an Atlas of the starry sky consisting of 56 maps, has come down to our days. Heweliusz depicted constellations on his maps inversed as if one looked at them from outside the celestial sphere.

His engraved drawings and inverted maps were used to create a celestial globe with 54 constellations and 1,564 stars from the astronomer's own catalogue. Heweliusz's globe had both already known Ursa Major and Ursa Minor, Capricornus and Draco, and the independently discovered Musca, Lacerta and Monoceros constellations.

The Moscow Planetarium had its Jan Heweliusz's globe made in 1983. Today, the big golden ball showing all the stars and constellations known to astronomers of the 12th century is the Urania Museum's highlight.

Foucault's pendulum

The idea to demonstrate the Earth's rotation using a pendulum belongs to the French astronomer and physicist Jean Bernard Léon Foucault. In 1851, at the Pantheon (Paris), he showed an experiment with a metal ball suspended from the top of the dome on a steel wire. Each time the pendulum swung, it left a new mark on a sandy path at the edge of the fence. After 32 hours, the pendulum made a complete revolution and returned to the starting point, proving the fact of planet's rotation around its own axis. Foucault was awarded the highest award of France, the Legion of Honour, for his pendulum experiment.

The largest Foucault pendulum in Russia is installed in the Lunarium of the Moscow Planetarium. A 50 kg ball hanging on a 16m long thread is swung over the limb scale oscillating in one plane. There is a small figure at the edge the ball is to touch later. While the pendulum is oscillating, its base continues rotating along with the Earth, so after a while the figure gets in the way of the ball to be knocked down.

Plasma ball 

The first plasma ball was invented by Nikola Tesla in 1894. The design called 'Electric light source' looked like a lamp with a glass bulb and one electrode. Scientist and inventor James Falk, who used to make unusual lamps for museums and private collectors in the 1970s, rendered the up-to-date look to the plasma ball.

A plasma ball is a glass sphere with a rarefied inert gas and an electrode inside. When the 30 KHz frequency voltage is applied to the electrodes, it starts the process of gas ionisation to make plasma featuring bright gas discharges shaped as lightning bolts.

Touch a plasma ball, and you will see magic. Lightning bolts immediately rush to the human hand. Bright electric ribbons are attracted to the body, acting as a current conductor. A mixture of gases is used in the ball to make multi-coloured discharges. Plasma balls ionise the air around, so, if you bring a fluorescent lamp closer, it will glow, too.

Lunarium offers to watch a plasma ball in all its splendour.

Wilson cloud chamber

Also, Lunarium offers to observe the movement of invisible charged particles in the Wilson cloud chamber. This device brought its inventor, physicist Charles Wilson (Scotland), a Nobel prize in 1927.

Wilson chamber is a small rectangular container with a glass lid and piston filled with alcohol, ether or water vapour. Based on the phenomenon of supersaturated steam condensation, the operation is simple: after a charged particle gets into a steam chamber, it collides with gas molecules and ionises them. The steam in the chamber condenses, with a white chain formed from the condensate droplets allowing to trace particle's trajectory.

The Wilson cloud chamber was one of the first devices to record particle movement. For a long time, it had been the only tool for studying cosmic rays and nuclear radiation.

Source: mos.ru

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