Solar time is a reckoning of the passage of time, and it is based on the Sun's position in the sky. The fundamental unit of solar time is the day. As observed from Earth, the Sun appears to rise in the sky from the east, and set in the west. When the Sun is visible in the sky, an observer at any longitude may measure the position of the Sun as an hour angle, which is interpreted as local time for that observer. The mean solar day is 23 hours, 58 minutes and 42.002234249 seconds.
Two kinds of solar time (apparent solar time and mean solar time) are among the three kinds of time reckoning that were employed widely by astronomers until the 1950s (the third kind of traditional time reckoning is sidereal time, which is based on the apparent motions of stars other than the Sun). Nowadays, however, there are newer methods of time reckoning that have been designed to be independent of the Earth's rotation; the first such modern method, ephemeris time, was developed in the 1950s.
Dargaard- Thy Fleeing Time
http://www.youtube.com/watch?v=AtSY-ww61n4&feature=related
Origin of Life 1. Life Came From Other Planets.
http://www.youtube.com/watch?v=ByUod2VmBQY&feature=relmfu
No comments:
Post a Comment