International Day of Planetariums Date in the current year: March 10, 2024

A planetarium is a type of theater build primarily for presenting educational and entertaining shows about the night sky and astronomy in general. Most planetariums have a large dome-shaped projection screen, onto which scenes of celestial objects are projected using a special technology. These scenes are usually accompanied by lectures or music.

The world’s first optical planetarium projector was made at the Carl Zeiss workshop in Jena in the early 1920s. It was exhibited at the Deutsches Museum in Munich. After World War II, other companies began to produce projectors for planetariums. They included Armand Spritz (United States), GoTo (Japan), Minolta (Japan), Ohira Tech Ltd. (Japan), and Evans & Sutherland (United States).

Today, most planetariums use digital projectors (interestingly, the IMAX system was originally conceived to operate on planetarium screens). Thanks to this technology, planetariums can demonstrate impressive fulldome shows in addition to traditional celestial scenes. Besides, the use of digital projectors has contributed to the emergence of portable planetariums that can be used in schools and universities, at exhibitions and other events.

The inaugural Day of Planetariums was organized in 1991 by the Italian Association of Planetaria. The initiative was supported by the International Planetarium Society (ISA) that unites planetariums, planetarium associations and planetarium professionals from 35 countries. In 1995, the Day of Planetariums went global for the first time.

Today, it is celebrated by regional and national planetarium associations in Europe, the Americas, Asia, and Australia. The observance was originally held on the Sunday before the Vernal Equinox, but now it is celebrated on the second Sunday of March.

The main goals of the International Day of Planetariums are to encourage collaboration within the international planetarium community and to popularize planetariums among the general public. According to the IPS official website, planetariums play an extremely important role in the present-day light-polluted world, where only a few stars can be see over large cities. Planetariums help people reconnect with the stars and learn more about them.

On the occasion of the International Day of Planetariums planetariums around the world host various events, such as lectures and exhibitions with discounted or free entry, so that as many people as possible can attend. Some planetariums host an entire week of events, which begins on the International Day of Planetariums or, on the contrary, ends with it. Planetariums that are closed on Sundays usually host events on the preceding Saturday.