Last updated: August 11, 2021

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Have you always been fascinated by space and its thousands of galaxies? With a planetarium you can bring the stars into your own four walls. But what should you consider before buying a so-called indoor planetarium?

In our planetarium test 2022, we present the best and most up-to-date models from the respective categories. We also give you important tips and tricks on the subject of hobby astronomy. Whether planetariums with transmitted light or laser projectors, you will find the best indoor planetariums on the market.




Summary

  • Basically, a planetarium is understood to be a large building with a dome for large-scale projections or a small indoor planetarium for home use.
  • With a room planetarium, an artificial starry sky can be projected onto a projection surface. Depending on the manufacturer, these devices are produced in different versions and designs.
  • In a planetarium, either a transmitted-light projector or a laser is installed. A transmitted-light projector requires projection screens, while a laser creates the image itself.

The Best Planetarium: Our Picks

Guide: Questions you should ask yourself before buying a planetarium

What is a planetarium?

A planetarium is either a building or a projector for home use. A planetarium for home use is also called a room planetarium or mobile planetarium.

A planetarium or star theatre was originally a building with a large dome on which a starry sky is projected for paying visitors. In a room planetarium, constellations are projected onto a projection surface such as a ceiling with the help of a built-in projector.

In Germany, there are some so-called large planetariums that are much more impressive than the domestic variety. However, these usually cost an entrance fee and are understandably not to be used in one's own four walls to fall asleep under the (artificial) starry sky.

Here we have listed the largest and best-known planetariums in Germany, including their locations.

City Name Number of visitors 2017
Berlin Planetarium am Insulaner 82,713
Berlin Zeiss-Großplanetarium 224,496
Bochum Zeiss Planetarium Bochum 274,810
Hamburg Planetarium Hamburg 380.000
Mannheim Mannheim Planetarium 105,000
Münster Münster Planetarium in the LWL Museum of Natural History 107,000
Nuremberg Nicolaus Copernicus Planetarium 70,874
Stuttgart Carl Zeiss Planetarium 136,000

In an indoor planetarium, on the other hand, the image is produced either by transmitted-light projection or laser projection. In a planetarium with a transmitted-light projector, an image is produced with a translucent projection screen. In a planetarium with a laser projector, however, the image is created by a laser itself.

Planetarium von außen

Originally, planetariums were buildings with a dome where you could admire a projected starry sky. Nowadays, planetariums are also available for home use. (Photo: Donations_are_appreciated / pixabay.com)

How much does a planetarium cost?

Planetariums for home use come in all price ranges. High-quality hobby devices can be bought for as little as 50 euros.

Some telescope manufacturers also offer planetariums for home use. Depending on the size of the built-in projector, the workmanship and the accessories included, these planetariums differ in price.

Less expensive models are available for as little as 50 to 100 euros. Expensive professional models starting at 10,000 euros come with a beamer, computer and their own software. With the help of this equipment, users can create their own projections of constellations and even programme their own films with the help of this star theatre.

How do you use a planetarium?

A planetarium with a transmitted-light projector works in the same way as a slide projector. With the help of projection discs, a starry sky is projected onto a ceiling.

Did you know that a planetarium was originally a device to show the course of the planets?

Until the 19th century, this is what was meant by a planetarium. Today, this original device, which shows the orbit of the planets around the sun, is called an "orrery".

The projection screens are transparent glass panes on which the reduced image of the starry sky is located. These are placed in the projection insert and pushed in front of the projector. The projector enlarges this image depending on the distance to the projection surface.

The motor built into most devices ensures that the projected stars move dynamically. The clear and sharp image of the projection can then be ensured by adjusting the focus ring.

Decision: What types of planetariums are there and which is the right one for you?

Basically, you can distinguish between two types of planetariums:

  • Planetarium with transmitted light projector
  • Planetarium with laser projector

Due to the construction of the optical components, the respective mode of operation of these planetariums is different. Therefore, there are advantages and disadvantages with each of these projection types. Depending on the purpose and preference, one or the other planetarium is more suitable.

In the next sections, the differences between the various types will be briefly explained so that you can decide for yourself which planetarium is right for you. In addition, the advantages and disadvantages of the individual telescopes are clearly compared.

Almost all planetariums produced for the home are equipped with a transmitted-light projector. An indoor planetarium is operated like a slide projector. Laser projectors are increasingly used in large planetariums.

Did you know that there are over 3200 projection planetariums worldwide?

There are probably even more, because many school planetariums are only used internally and are therefore not known. In the USA alone, 1500 planetariums are known to exist. (Status: end of 2006)

How does a planetarium with a transmitted-light projector work and what are its advantages and disadvantages?

To operate a transmitted-light projector, translucent projection screens are needed to create the image. The optics work in exactly the same way as with a slide projector.

To prevent overheating, most transmitted-light projectors are fitted with a fan. It ensures that the projector does not overheat. Depending on the size and type of ventilation, however, it can be very loud.

In contrast to a reflected-light projector, a transmitted-light projector can only project translucent originals. Usually, several projection screens are included in the scope of delivery so that several objects can be projected.

For most of these planetariums, accessories such as additional projection screens can be purchased. With a selection of images, you can conjure up a variety of celestial objects and star images on the wall for you, your family and your friends.

Advantages
  • Cheaper than laser projectors
  • Images are interchangeable
  • Easy to use
Disadvantages
  • Projection screens needed
  • Loud fan

How does a planetarium with a laser projector work and what are its advantages and disadvantages?

To operate a laser projector, the image to be projected is created directly by the laser itself. The laser is pre-programmed and in most cases can cast several preset star images onto the wall.

Laser projectors are extremely low-maintenance and in most cases only require readjustment over time. The laser is particularly well suited for starry skies, as it can display colours true to life.

Absolute black can also be displayed with the help of the projector. For safety reasons, it is not recommended to look directly into the optics with the naked eyes, as this could cause long-term damage.

A planetarium with laser optics cannot usually be expanded with additional star images. In very few cases can these laser projectors be reprogrammed. You should therefore always look at the images before deciding on a particular planetarium.

Advantages
  • Sharp image
  • No projection screens needed
Disadvantages
  • Images not interchangeable
  • More expensive than transmitted light projectors

Buying criteria: Use these factors to compare and evaluate planetariums

This section describes the most important factors that can be used to compare and evaluate planetariums. The following criteria will help you to find the right planetarium for you and thus make your purchase decision easier:

  • Processing
  • Article size
  • Article weight
  • Projection distance
  • Projection surface
  • Design
  • Projection type

In the following chapters, the individual categories are described in more detail. You can then decide for yourself how these comparison criteria should be classified.

Processing

The workmanship of a product determines not only the external appearance of the planetarium, but also the quality of the projected image.

A good planetarium is characterised by a clean production of the optical and mechanical components and the use of high-quality materials. The good workmanship of a planetarium is therefore decisive for the high quality of the projection.

Item size

Most modern indoor planetariums are very handy and usually differ only marginally in size. Nevertheless, many customers attach great importance to the mobility of their planetarium.

With a small projector design, the planetarium can be taken anywhere to be equipped with a portable starry sky for all occasions.

Sternenprojektor

Planetariums work differently depending on the projector. For home planetariums, mostly transmitted light projectors are used because they are the easiest to use. They work similarly to a slide projector. (Photo: Hans / pixabay.com)

Item weight

Not only the item size, but also the weight determines whether the product is a stationary or mobile planetarium.

A heavy planetarium is cumbersome to carry around and is therefore better suited as a stationary device. An indoor planetarium with a low weight, such as the Kosmos 676810 Planetarium, on the other hand, is ideal for mobile use and, when carried in a bag, does not cause frustration or shoulder pain, even on long journeys.

Projection distance

The projection distance determines the maximum distance at which the planetarium should be set up from the projection surface.

Most manufacturers specify this value for their products. Maintaining this distance ensures that the image is clear and sharp. If this distance is exceeded, the image will be blurred and distorted. The manufacturer of the Bresser Junior AstroPlanetarium Deluxe, for example, specifies a maximum projection distance of 3 m.

Projection surface

The projection area indicates how large the projection of the image is at a certain distance. It is therefore also dependent on the projection distance.

If the projection surface of the product is large, as is the case with the Sega Toys HomeStar - Original Home Planetarium, this is also referred to as high immersion. This term refers to the ability to make a virtual image feel real and genuine to the user.

Design

Many customers attach great importance to the design of a product. An appealing colour combination can determine the final purchase decision for many. Whether consciously or unconsciously, many buyers also include visual criteria such as design in their purchase decision when choosing a product.

Thus, an unfavourably chosen colour combination can also ensure that the product appears unattractive to the customer. The National Geographic Astro Planetarium Multimedia is a good example of a planetarium whose design was mentioned very positively by many customers.

Projection type

Basically, planetariums can be distinguished by their built-in projector. The built-in technology determines how the image is created.

In the case of indoor planetariums, it is either a transmitted-light projector or a laser projector. A so-called transmitted-light projector works like an ordinary slide projector. The image of an inserted projection screen is projected onto a projection surface in enlarged form.

In a laser projector, a pre-programmed laser generates the actual image. While transmitted-light projection is moving more and more into home use, many large star theatres are increasingly using laser projection.

Almost all indoor planetariums are equipped with a built-in transmitted-light projector. These planetariums have the advantage that they do not require a computer for reprogramming due to exchangeable projection screens and are very easy to operate.

Facts worth knowing about planetariums

Who invented the planetarium?

In 1923, the first planetarium projector was completed, based on plans drawn up by an engineer from the Carl Zeiss company. The plans for the construction of the first modern planetarium were drawn up in 1919 by engineer Walther Bauersfeld. It was not until four years later that the first planetarium projector was built by the Carl Zeiss company.

In 1925, the first projection planetarium was opened in the Deutsches Museum in Munich. In 1926, the planetarium was opened in Barmen in Wuppertal with the Model II, which could also project the southern starry sky for the first time.

The first planetariums for home use were not manufactured until the 1950s, originally for use in schools. Whereas previously only large projectors were possible due to the complex construction, hobby astronomers could now buy small devices for their own use for the first time.

Image source: Pixabay.com / FelixMittermeier

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