An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

1a) General: Extending well inward from an outer surface or back from an edge.
1b) Great in measure; intense. → deep exposure.
1c) Of colors, dark and vivid.
2) The deep part of a body of water, especially an area of the ocean floor having a depth greater than 5400 meters (Dictionary.com).

O.E. deop, from P.Gmc. *deupaz, from PIE *d(e)u- "deep, hollow."

Žarf "deep;" variants Gilaki jalf, julf, jal; Tabari jol, jal, jul; Baluci jahl, johl; Kermâni jarr "deep;" Mid.Pers. zufr; Av. jafra- "deep."
Gowd, probably ultimately from PIE root *g^wādh- "to sink, submerge;" cf. Av. vigāθô- "ravines, gorges;" Skt. gādha- "depth; shallow;" Gk. bessa "gorge, ravine."

An exposure in which the detector shutter remains open for a relatively long time in order to bring out the weaker features of the observed object. In practice a deep exposure with a CCD detector is usually obtained from co-addition of shorter exposures.

→ deep; → exposure.

An area on the sky whose image is obtained with a deep exposure, such as → Hubble Deep Field.

→ deep; → field.

An image obtained using a deep exposure to reveal the weak features of the object.

→ deep; → image.

The time-scale of geologic processes which is millions or billions of years in contrast to the few thousand years claimed by supporters of the → creationism. The concept of "deep time" was first described in 1788 by the Scottish geologist James Hutton (1726-1797) in the Transactions of the Royal Society of Edinburgh. The term was coined by the American author John McPhee (1931-).

→ deep; → time.

An image of a small region in the constellation → Ursa Major, based on the results of a series of observations by the → Hubble Space Telescope. The image was assembled from 342 separate exposures taken over ten consecutive days between December 18 and December 28, 1995. It covers an area 144 arcseconds across.

→ Hubble; → deep; → field.