Glossary term: Espejo
Description: Un espejo es un dispositivo óptico que refleja la luz desde su superficie. Los espejos convexos dispersan los haces de luz, mientras que los espejos cóncavos los concentran. Los espejos cóncavos pueden diseñarse para enfocar haces de luz paralelos en un punto. La mayoría de los telescopios modernos utilizan grandes espejos cóncavos como superficie colectora principal.
El cuerpo principal de la mayoría de los espejos utilizados en los telescopios astronómicos está fabricado en vidrio. Otros materiales que a veces se utilizan para el cuerpo del espejo son la cerámica y los metales. El cuerpo del espejo se lija (o se le da otra forma) y se pule, y si el material no es ya reflectante, se aplica un fino recubrimiento metálico a la superficie. El aluminio es el material de recubrimiento más habitual, aunque el oro o la plata son alternativas.
En el caso de los telescopios de más de unos seis metros de diámetro, resulta difícil fundir y soportar espejos de cristal de tal envergadura. Por ello, algunos de los telescopios más grandes del mundo utilizan actualmente numerosos espejos más pequeños que se disponen juntos para enfocar la luz como si se tratara de un único espejo gigante.
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Term and definition status: The original definition of this term in English have been approved by a research astronomer and a teacher The translation of this term and its definition is still awaiting approval
The OAE Multilingual Glossary is a project of the IAU Office of Astronomy for Education (OAE) in collaboration with the IAU Office of Astronomy Outreach (OAO). The terms and definitions were chosen, written and reviewed by a collective effort from the OAE, the OAE Centers and Nodes, the OAE National Astronomy Education Coordinators (NAECs) and other volunteers. You can find a full list of credits here. All glossary terms and their definitions are released under a Creative Commons CC BY-4.0 license and should be credited to "IAU OAE".
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Related Media
Gemini South's primary mirror and telescope structure
Caption: This is the primary mirror and supporting structure of a large optical telescope at the Gemini South Observatory in Chile. The primary mirror is the largest and most important mirror in a reflecting telescope: its gently curved surface gathers light from faint stars, galaxies, and nebulae and reflects that light to a focal point. At this focal point light is either fed directly in to an instrument to record spectra and images or redirected to such an instrument by a series of further mirrors. The sturdy metal framework around the primary mirros keeps the mirror precisely aligned and protected while the telescope moves to track objects across the sky.
In telescopes that use mirrors instead of lenses, such as this one, the mirror is what collects and focuses the light from distant celestial objects. Larger mirrors can capture more light, allowing astronomers to see fainter and more distant objects. A larger primary mirror can also take sharper images of the sky, but this is often negated by the blurring effect of the Earth's atmopshere. A primary mirror must be perfectly smooth to tolerances of fractions of a wavelength of light so that it produces sharp, clear images. We can think of the primary mirror as the “eye” of the telescope that looks out into space, with its shape and support enabling powerful astronomical observations.
Credit: International Gemini Observatory/NOIRLab/NSF/AURA/M. Paredes
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