Astronomy Terms From Chapter 6 Of The Solar System

Front 1

electromagnetic radiation

Back 1

Changing electric and magnetic fields taht travel through space and transfer energy from one place to another-- for example, light, radio waves, and the like

Front 2

wavelength

Back 2

The distance between successive peaks or troughs of a wave

Front 3

frequency

Back 3

The number of times a given event occurs in a given time; for a wave, the number of cycles that pass the observer in 1 second

Front 4

nanometer

Back 4

A unit of length equal to 10^-9 m

Front 5

Angstrom

Back 5

A unit of distance; 1 Angstrom = 10^-10 m; often used to measure the wavelength of light

Front 6

photon

Back 6

A quantum of electromagnetic energy; carries an amount of energy that depends inversely on its wavelength

Front 7

infrared radiation

Back 7

Electromagnetic radiation with wavelengths intermediate between visible light and radio waves

Front 8

ultraviolet radiation

Back 8

Electromagnetic radiation with wavelengths shorter than visible light but longer than X rays

Front 9

atmospheric window

Back 9

Wavelength regions in which Earth's atmosphere is transparent-- at visual, infrared, and radio wavelengths

Front 10

focal length

Back 10

The distance from a lens to the point where it focuses parallel rays of light

Front 11

refracting telescope

Back 11

A telescope that forms images by bending (refracting) light with a lens.

Front 12

reflecting telescope

Back 12

A telescope that uses a concave mirror to focus light into an image

Front 13

primary lens, mirror

Back 13

The main optical element in an astronomical telescope. The large lens at the top of the telescope tube or the large mirror at the bottom.

Front 14

objective lens, mirror

Back 14

The main optical element in an astronomical telescope. The large lens at the top of the telescope or large mirror at the bottom.

Front 15

eyepiece

Back 15

A short-focal-length lens used to enlarge the image in a telescoe; the lens nearest the eye.

Front 16

chromatic aberration

Back 16

A distortion found in refracting telescopes because lenses focus different colors at slightly different distances. Images are consequently surrounded by color fringes.

Front 17

achromatic lens

Back 17

A telescope lens composed of two lenses ground from different kinds of glass and designed to bring two selected colors to the same focus and correct for chromatic aberration

Front 18

light-gathering power

Back 18

The ability of a telescope to collect light; proportional to the area of the telescope objective lens or mirror.

Front 19

resolving power

Back 19

The ability of a telescope to reveal fine detail; depends on the diameter of the telescope objective.

Front 20

diffraction fringe

Back 20

Blurred fringe surrounding any image caused by the wave properties of light. Because of this, no image detail smaller than the fringe can be seen.

Front 21

magnifying power

Back 21

The ability of a telescope to make an image larger.

Front 22

light pollution

Back 22

The illumination of the night sky by waste light from cities and outdoor lighting, which prevents the observation of faint objects.

Front 23

prime focus

Back 23

The point at which the objective mirror forms an image in a reflecting telescope.

Front 24

secondary mirror

Back 24

in a reflecting telescope, the mirror that reflects the light to a point of easy observation.

Front 25

Cassegrain focus

Back 25

The optical design of a reflecting telescope in which the secondary mirror reflects light back down he tube through a hole in the center of the objective mirror

Front 26

Newtonian focus

Back 26

The focal arrangement of a reflecting telescope in which a diagonal mirror reflects light out the side of the telescope tube for easier access.

Front 27

Schmidt-Cassegrain focus

Back 27

The optical design of a reflecting telescope in which a thin correecting lens is places at the top of a Cassegrain telescope.

Front 28

sidereal drive

Back 28

The motor and gears on a telescope that turn it westward to keep it pointed at a star.

Front 29

equatorial mounting

Back 29

A telescope mounting that allows motion parallel to an perpendicular to the celestial equator.

Front 30

polar axis

Back 30

The axis around which a celestial body rotates

Front 31

alt-azimuth moutning

Back 31

A telescope mounting capable of motion parallel and perpendicular to the horizon

Front 32

active optics

Back 32

Optical elements whose position or shape is continuously controlled by comptuers

Front 33

adaptive optics

Back 33

Computer-controlled telescope mirrors that can at least partially compensate for seeing.

Front 34

interferometry

Back 34

The observing technique in which separated telescopes combine to produce a virtual telescope with the resolution of a much-larger diameter telescope.

Front 35

charge-coupled device

Back 35

An electronic device consisting of a large array of light-sensitive elements used to record very faint images

Front 36

false-color image

Back 36

A representation of graphical data in which the colors are altered or added to reveal details.

Front 37

spectrograph

Back 37

A device that separates light by wavelength to produce a spectrum

Front 38

grating

Back 38

A piece of material in which numerous microscopic parallel lines are scribed; light encountering a grating is dispersed to form a spectrum.

Front 39

comparison spectrum

Back 39

A spectrum of known spectral lines used to identify unknown wavelengths in an object's spectrum.

Front 40

radio interferometer

Back 40

Two or more radio telescopes that combine their signals to achieve the resolving power of a larger telescope

Front 41

cosmic ray

Back 41

A subatomic particle traveling at tremendous velocity that strikes Earth's atmosphere from space.