Astronomy Chapter 5 Vocab

Front 1

adaptive optics

Back 1

A technique for adjusting a telescope's mirror or other optical parts to compensate for atmospheric distortions, such as seeing, thereby giving a sharper image.

Front 2

atmospheric window

Back 2

A wavelength band in which our atmosphere absorbs little radiation. For example, on Earth the visible window ranges from about 300 to 700 nanometers, allowing the light we can see with our eyes to pass through the atmosphere.

Front 3

CCD

Back 3

Charge-coupled device. An electronic device that records the intensity of light falling on it. CCDs have replaced film in most astronomical applications.

Front 4

diffraction

Back 4

A bending of the path of light (or other electromagnetic waves) as it passes through an opening or around an obstacle. Diffraction limits the ability to distinguish fine details in images.

Front 5

dispersion

Back 5

The spreading of light or other electromagnetic radiation into a spectrum. A rainbow is an example of dispersion of light caused by raindrops.

Front 6

interferometer

Back 6

A device consisting of two or more telescopes connected together to work as a single instrument. Used to obtain a high resolving power, the ability to see small-scale features. Interferometer telescopes have been constructed operating at radio, infrared, and visible wavelengths.

Front 7

light-gathering power

Back 7

A measure of the ability of a telescope (or other device) to collect light. It is generally proportional to the area of the telescope's mirror of lens. For example, a telescope with a 6-inch diameter lens has a four times larger light-gathering power than a telescope with a 3-in diameter lens.

Front 8

reflector

Back 8

A telescope that uses a mirror to collect and focus light.

Front 9

refraction

Back 9

The bending of light when it passes through one substance and enters another.

Front 10

refractor

Back 10

A telescope that uses a lens to collect and focus light.

Front 11

resolving power

Back 11

The ability of a telescope or instrument to discern fine details. Larger-diameter-telescopes have greater (that is, better) resolving power.

Front 12

scintillation

Back 12

The twinkling of stars caused by the atmosphere.

Front 13

seeing

Back 13

A measure of the steadiness of the atmosphere during astronomical observations. Under conditions of bad seeing, fine details are difficult to see. Bad seeing results from atmospheric irregularities moving between the telescope and the object being observed.