Beginning Astronomy

Altitude - The angular distance of a celestial object above the horizon

aphelion - The point on the orbit of a celestial body that is farthest from the sun.

asteroid - Any of numerous small celestial bodies that revolve around the sun

azimuth - The horizontal angle of the observer's bearing in surveying, measured clockwise from a referent direction

coma - Dust or gas surrounding a comet .

comet - Relatively small extraterrestrial body consisting of a frozen mass that travels around the sun.

deep sky/space - Any object beyond our solar system.

magnitude - A rating of the brightness of a celestial body. The lower the number the brighter the object.

meteor - any of the small solid extraterrestrial bodies that hits the earth's atmosphere

meteorite - A stony or metallic mass of matter that has fallen to the earth's surface from outer space.

meteoroid - A solid body, moving in space, that is smaller than an asteroid

perihelion - The point in its orbit where a celestial body is closest to the Sun.

zenith - The point in the sky directly above the observer.

alt-azimuth mount - A type of mount used for telescopes. This mount pivots in two directions vertically and horizontally and is not polar aligned.

Aperture - The diameter of the telescopes main lens or mirror.

barlow lens - A lense placed between the scope and eyepiece which doubles or sometimes triples the magnification depending on its specifications.

catadioptric - scope using combination of mirrors and lenses. Example : Schmidt Cassegrain - Maksutov Cassegrain

CCD - Charged Coupled Device - A chip which can capture astro images found in a webcam and also higher end astro imagers.

chromatic aberration - the negative effect when light different colors of light are not focused at the same point.

declination - The angular distance to a point on a celestial object, measured north or south from the celestial equator.

DSLR - Digital Single Lense Reflex - Basically your high end digital camera can be used to capture astro images with the right adapter.

equatorial mount - A mount in which one of the telescopes axis is aligned with the rotation of the earth so that the scope only needs to spin in one axis to track the apparent movement of the stars. Example german equatorial or a wedged fork mount. This is the best type of mount for astrophotography.

focal length - The length of the telescope's light path.

focal ratio - Focal length divided by the aperture example.

OTA - Optical Telescope Assembly - The main optical assembly including the lense or mirrors.

polar alignment - Alignment in which one of the telescopes axis is aligned with the rotation of the earth so that the scope only needs to spin in one axis to track the apparent movement of the stars.

reflector - A telescope design utilizing MIRRORS to magnify an image.

refractor - A telescope design utilizing transparent LENSES to refract the light for magnification.

right ascension - A coordinate for measuring the east-west positions of celestial bodies.