Solar Time
Related Category: Astronomy: General
time defined by the position of the sun. The solar day is the time it takes for the sun to return to the same meridian in the sky. Local solar time is measured by a sundial.
Solar time
Solar time is based on the idea that when the sun reaches its highest point in the sky, it is noon.
solar time
Home ... Science and Technology Astronomy and Space Exploration Astronomy: General ...
Essential reading Compare
side-by-side A Dictionary of Astronomy A Dictionary of Astronomy The Columbia Encyclopedia, ...
Mean Solar Time
A time based on a hypothetical moving uniformly along the celestial equator. The fluctuations have ranged between ± 30 seconds over the last 300 years.
solar time: see time (types of).
solstices: (Summer ~, Winter ~) literally, 'Sun stands still'.
Solar Time Time measured with respect to the Sun. See the tutorial on Time.
Solar times are measures of the apparent position of the Sun on the celestial sphere. They are not actually the physical time, but rather hour angles, that is, angles expressed in time units....
s long, which has an error of about one day
Day ...
Mean solar time -- Time based on an average of the variations caused by Earth's non-circular orbit. The 24-hour day is based on mean solar time.
Mercury -- First planet from the sun, a terrestrial planet.
Mean Solar Time
A measure of time based conceptually on the diurnal motion of the fictitious mean sun, under the assumption that the Earth's rate of rotation is constant.
Mean Sun ...
Mean Solar Time - Time kept according to the average length of the solar day
Megaparsec (Mpc) - A unit of distance, equal to 1 million parsecs, often used to describe the distances of objects beyond the Local Group ...
solar time - (n.)
A system of time-keeping with respect to the sun such that the sun is overhead of a given location at noon.
solar wind - (n.) ...
Mean solar time of the meridian (0° longitude) at Greenwich, England, from which other time zones are calculated.
(363) Local Solar Time in Iceland
7d. Shape and size of the Earth
(26) Why does the Earth rotate? Why is it a sphere?
(56) Who first proposed a round Earth?
(76) Distance to the Horizon ...
solar time (NASA SP-7, 1965) Time based upon the rotation of the earth relative to the sun.
Solar time may be designated as mean or astronomical if the mean sun is the reference, or apparent if the apparent sun is the reference.
The apparent solar time (based on the actual sun) and the mean solar time (based on the mean sun) can differ by as much as 15 minutes at certain seasons. The difference between the two is called the equation of time.
09054 seconds of mean solar time. sidereal hour angle (abbr SHA). Angular distance west of the vernal equinox; the arc of the celestial equator, or the angle at the celestial pole, ...
sidereal month The average period of revolution of the moon around the earth in reference to a fixed star, equal to 27 days, 7 hours, 43 minutes in units of mean solar time.
For mission operations purposes, they defined a time scale that would match the clock used for the mission to the apparent solar time about halfway through the nominal 90-sol prime mission.
The instruments recorded data throughout the descent until about 1 minute after impact at 03:00 local solar time (LST) except for the entry pressure measurements, terminated at 0.
Sidereal Time and Solar Time
In using the sky for timekeeping, we must define a reference point to determine when a cycle of the required motion has been completed.
The precession of the Earth's rotation axis introduces another difference between sidereal time and solar time. This is seen in how the year is measured. A year is defined as the orbital period of the Earth.
(a) The difference between Apparent and Mean Solar Time. At Greenwich, apparent Solar noon varies between 11h44m05s and 12h14m19s. Maximum contribution from Earth's orbital eccentricity, ~ 8 min; from Earth's obliquity, ~ 10 min.
Every location on the Earth falls within a particular time zone, where all clocks are set to the same mean solar time. These regions cover around 15 degrees of longitude.
BOTTOM IMAGE: Anaglyphic stereoimage created from the 'monster pan' sequence, acquired in four sections between about 8:30 and 15:00 local solar time on sol 3.
Time, Standard Mean (SMT)
Mean solar time for some standard adopted longitude (for example, Eastern Standard Time, Central European Time, Mountain or Pacific Standard Times; see: scholar pages about time).
Equation of Time The difference between apparent and mean solar time.
SIDEREAL TIME - Time measured in relation to the fixed stars: the length of a sidereal day is 23 hr, 56 min, 4.09 sec of mean solar time.
SIDERITE - An obsolete term for an iron meteorite.
10 : A ___________ is the time taken for any object in the Solar System (such as the Moon) to return to the same position relative to the Sun as seen from Earth.
year
solar time
sidereal period
synodic period ...
Sidereal day: The time required for Earth to revolve 360o with respect to a celestial object outside the solar system. About 23 hours 56 minutes duration in terms of solar time.
 See also: Solar, Time, Earth, Sun, Astronomy
|
