Image Spacer
Site Index | Phone Directory | Search
Long Beach City College Image Spacer
Site Navigation
Planetarium Home
Visiting the Planetarium
What is a Planetarium?
Planned and Completed Planetarium Upgrades
Show Schedule
Astronomy Classes
Other Information
Physical Science Home
Astronomy Home Page
Professor MacCallum
Professor Sholle
External Links
Get Adobe Reader
Image SpacerAdmissionsCounselingDisabled Student ServicesEOPSFinancial Aid
Gray rule
What is a Planetarium?


Although a planetarium and an observatory both involve domes and both involve astronomy, they are not the same thing. A planetarium involves the projection of astronomical images such as stars, planets, the moon, the sun and other objects onto the inner surface of a dome, in order to visualize what the night sky looks like for the purpose of educational instruction. A planetarium can be used in the daytime to visualize the night sky, and can present a visualization of the sky to city residents that is otherwise only available from dark viewing locations located far from brightly lit urban areas. Modern planetariums can also do much more than this.

An observatory houses a telescope that is used to view, photograph or take digital images of astronomical objects in the sky. Traditionally telescopes operated only at visible wavelengths, that is, at wavelengths of electromagnetic radiation that are visible to the human eye. In the last half of the twentieth century astronomers started building and using telescopes that operated at radio, infrared, ultraviolet, X-ray and gamma ray wavelengths. Because of the opacity of the atmosphere, only visible, radio and near-infrared telescopes are usable from the surface of the earth. To use other wavelengths, a telescope must be placed into orbit above the earth's atmosphere. Observatories are typically used for research in order to make discoveries about the nature of the universe. Some observatories are used for educational instructional purposes, such as the observatory on the roof of the Math-Science (D) building. The dome of an observatory is used to protect the telescope from the weather when the telescope is not being used, and the dome opens at night to allow the telescope to view the sky.