Telescopes

Front

Telescope Noun

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[tel-uh-skohp]

Back

Telescope

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An optical instrument that gathers a large amount of light from a distant source and brings it into focus.

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Example: This diagram shows how a refracting telescope works. A large lens gathers and bends light, and a small lens magnifies this light for your eye.

Front

Refracting Telescope Noun

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[ri-frakt-ing tel-uh-skohp]

Back

Refracting Telescope

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An optical telescope that uses a primary objective lens to bend and concentrate light from distant objects into a focus.

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Example: A refracting telescope uses a large lens to gather and bend (refract) light to a focal point, and a smaller lens magnifies this light.

Front

Reflecting Telescope Noun

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[ri-flekt-ing tel-uh-skohp]

Back

Reflecting Telescope

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An optical telescope that utilizes a curved mirror, rather than a lens, to collect and focus incoming light.

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Example: This diagram shows how a reflecting telescope works: a large curved mirror gathers and reflects light to a smaller mirror, which then directs the image to an eyepiece.

Front

Refraction Noun

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[ri-frak-shuhn]

Back

Refraction

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The bending of a light beam as it travels from one transparent medium, such as air, into another, like glass.

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Example: This diagram shows a light ray bending as it passes from a less dense medium (air) to a more dense medium (water), demonstrating refraction.

Front

Chromatic Aberration Noun

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[kroh-mat-ik ab-uh-rey-shuhn]

Back

Chromatic Aberration

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A lens distortion where different colors of light are focused at different points, creating a colored fringe around an image.

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Example: A lens in a telescope bends different colors of light by different amounts, causing them to focus at separate points and creating a blurry image.

Front

Electromagnetic Spectrum Noun

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[ih-lek-troh-mag-net-ik spek-truhm]

Back

Electromagnetic Spectrum

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The complete range of radiant energy carried by electromagnetic waves, from radio waves to gamma rays, including visible light.

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Example: This diagram shows the electromagnetic spectrum, the full range of light waves, from high-energy gamma rays to low-energy radio waves, including visible light.

Front

Radiant Energy Noun

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[rey-dee-uhnt en-er-jee]

Back

Radiant Energy

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The energy that is transported by electromagnetic waves and emitted into space by celestial objects such as stars.

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Example: This diagram shows radiant energy, in the form of waves, traveling from the Sun through the vacuum of space to the Earth.

Front

Wavelength Noun

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[weyv-lengkth]

Back

Wavelength

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A key characteristic of an electromagnetic wave that defines its type of radiant energy and its position on the spectrum.

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Example: This diagram shows that light travels in waves. Wavelength is the distance between wave crests, and different colors of light have different, measurable wavelengths.

Front

Light-gathering power Noun

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[lahyt-gath-er-ing pou-er]

Back

Light-gathering power

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A telescope's ability to collect light, which is directly proportional to the area of its primary mirror or objective lens.

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Example: A telescope with a larger objective lens (the bigger circle) can collect more light, creating a brighter image than a telescope with a smaller objective.

Front

Resolving power Noun

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[ri-zolv-ing pou-er]

Back

Resolving power

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The measure of a telescope's capacity to separate two closely spaced objects and reveal fine details within an image.

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Example: This image shows how a telescope's resolving power determines if two close objects, like stars, appear as one blurry spot or as two distinct points.