Planetarium

A planetarium is a special kind of theatre where people can learn about and enjoy shows about astronomy and the night sky. It is also sometimes used for training in celestial navigation. Most planetariums have a big dome-shaped projection screen. On this screen, images of stars, planets, and other celestial objects appear and move to look just like they do in the real sky. These images can be created in many ways, like using a star ball, slide projector, video, fulldome projectors, or lasers.

Planetariums come in many different sizes. Some are very large, like the one in St. Petersburg, Russia. Others are small and portable, where people sit on the floor. The largest planetarium in the Western Hemisphere is at the Liberty Science Center in New Jersey. In India, the Birla Planetarium, Kolkata can seat the most people. In New York City, the Hayden Planetarium at the American Museum of Natural History has many seats.

The word planetarium is sometimes used to talk about other tools that show the Solar System, like computer programs or models called an orrery. There is even special Planetarium software that creates images of the sky on a computer screen. A planetarian is a person who works at a planetarium.

History

For specific dates and events in the historical influences on and development of planetaria, see timeline of planetariums.

Early

The ancient Greek polymath Archimedes created a simple device that could show the movements of the Sun and the Moon and the planets. Later discoveries showed that such devices existed in antiquity. Some devices, like the Globe of Gottorf built around 1650, had paintings of stars inside. These early devices are now called orreries. Many modern planetariums have projection orreries that show the Solar System on a dome.

In 1229, Frederick II of Hohenstaufen, the Holy Roman Emperor, brought back a tent with holes representing stars or planets. Inside, a spinning table made the tent show the movement of these objects.

20th century

In 1905, Oskar von Miller worked with engineers to build a large mechanical planetarium that could show the movements of the planets and stars. This was first shown in 1924.

Soon after, a new design was created that could project images of the night sky onto a dome. The first of these was shown in Munich in 1923.

Zeiss planetariums became very popular, with new ones opening in Rome, Chicago, and Osaka.

After World War II

After World War II, Germany was divided, and the Zeiss company split as well. Both parts continued to make planetariums. During this time, many new planetariums were built around the world.

The Space Race in the 1950s and 60s led to many new planetariums being built in schools in the United States.

Armand Spitz created small, affordable planetariums that could be used in schools. His models could show thousands of stars and had moving parts for different views of the sky.

In the 1960s, companies in Japan began making planetariums, with one model being placed in every elementary school in Japan.

During the 1970s, new systems like OmniMax allowed planetariums to show wide-screen films on their domes.

In 1977, the first portable planetarium was created, allowing schools to easily set up a star show.

When Germany reunified in 1989, the two Zeiss companies joined again and made planetariums of many different sizes.

Computerized planetaria

In 1983, the first digital planetarium projector was installed. This used computer graphics to show the night sky from any point in space and time. Newer projectors can show any image on the dome.

Technology

Planetariums have big dome-shaped screens. Stars, planets, and other space objects appear to move on these screens. The domes can be small or large, holding just one person or many hundreds. Some domes are fixed buildings. Others are portable and can be set up quickly for shows in schools or community centers.

Older planetariums used special machines to project stars onto the dome. Today, many planetariums use computers. They create images of space and show them on the dome using digital projectors. This lets them show detailed and colorful pictures of the night sky, including planets, stars, and the Milky Way.

Show content

Most planetariums show programs to the public. These shows often talk about what we can see in the night sky tonight or connect the sky to special events like the Christmas star. Many places have a live speaker who can answer questions.

Since the early 1990s, modern planetariums have used special 3-D technology. This lets the audience see space from any point, not just from Earth. This helps people understand that space has depth, and the stars are not just stuck on a big ball. For example, a show can take viewers close to constellations like Orion, showing that the stars in the shape are actually very far apart. This can help people learn more about the Solar System and space beyond.