2 articles for "Delta T"

**Delta T**[Astro*Index]

Defined as **ephemeris time** minus **universal time** (*Delta-T = ET - UT*). A correction for this difference is applied to the Universal Time to obtain Ephemeris Time, which is used to determine a planetary position from an ephemeris.

See also:

♦ Ephemeris Time ♦ Universal Time

**Delta T**[Munkasey M.]

The time correction obtained from the direct observation of heavenly bodies which must be applied to Universal Time to obtain Ephemeris Time. These corrections arise from the apparent speeding up or slowing down of the Earth in its Solar orbit.

See also:

♦ Ephemeris Time ♦ Universal Time

Astro*Index Copyright © 1997 Michael Erlewine