Gmt Time In Seconds

In this case, you can see that currentlocal is 21600 seconds behind GMT, which stands for Greenwich Mean Time. GMT is the time zone with no UTC offset: UTC±00:00. 21600 seconds divided by seconds per hour (3,600) means that currentlocal time is GMT-06:00 (or UTC-06:00). GMT Time converter, compare UK and Local. Enter your location or any place, city, location for more comparisons. British Summer Time Dates. Daylight saving time begin and end dates, Sunday 01:00 GMT (1.00am Greenwich Mean Time): Proposals have been made from time to time about changing the UK's time zone to Central European Time. Greenwich Mean Time (GMT) GMT is a time system referring to the mean solar time at the Royal Observatory in Greenwich, London. Staples chair hyken. Later on it became an international time standard. GMT and Universal Standard Time (UTC) can be seen as the same as long as fractions of a second are not important. If your PC clock is accurate to a second then the other time scales displayed above will also be accurate to within one second. UTC, Coordinated Universal Time, popularly known as GMT (Greenwich Mean Time), or Zulu time. Local time differs from UTC by the number of hours of your timezone. GPS, Global Positioning System time, is the atomic time scale implemented by the atomic clocks in the GPS ground control stations and the GPS satellites themselves. GPS time was zero at 0h 6-Jan-1980.

The mission of the family of websites & services is to synchronize humans and machines around the world.
This mission statement has a strong foundation in metaphysics: Synchronization is a common denominator for the forces that govern the universe and is a sign of consciousness. For example.Seconds
  • Particles in stars and planets are synchronized as they spin around their own axii and along other trajectories, just as solar systems are synchronized in their motion around the center of the galaxy
  • Cells in every living thing are synchronized in terms of function just as they are synchronized against day / night cycles
I consider synchronization an all-encompassing phenomenon driven by “conscious features” from large to small through spatial notions like gravity / attraction and informational notions like communication / intent.
Humans have expanded in spatial & informational terms greatly in the last centuries to the point that travel and access to information is available around the planet and even beyond, through proven technologies.
However, “temporal navigation” references used by the general public seem to remain arbitrary, ambiguous and limited in terms of device use & engineering.
In general use, i made it my purpose to help people and machines synchronize, by offering a family of free browser / HTTP-based services with lightweight protocols.

Gmt Time In Seconds Now

Beyond general use, there is also a need to synchronize the “synchronizers” at the software engineering level, by offering straight-forward browser-based time conversion tools and by crystallizing time engineering standards.
But more importantly, the aim is to connect time engineering knowledge with time conversion and time navigation by using a functional red line that defines a strategy, such as it is, for time-keeping in the future.

Five Millennium Canon of Lunar Eclipses [Espenak and Meeus]

Greenwich Mean Time

For thousands of years, time has been measured using the length of the solar day. This is the interval between two successive returns of the Sun to an observer's local meridian. Unfortunately, the length of the apparent solar day can vary by tens of seconds over the course of a year. Earth's elliptical orbit around the Sun and the 23.5° inclination of Earth's axis of rotation are responsible for these variations. Apparent solar time was eventually replaced by mean solar time because it provides for a uniform time scale. The key to mean solar time is the mean solar day, which has a constant length of 24 hours throughout the year.

Mean solar time on the 0° longitude meridian in Greenwich, England is known as Greenwich Mean Time (GMT). At the International Meridian Conference of 1884, GMT[1] was adopted as the reference time for all clocks around the world. It was also agreed that all longitudes would be measured east or west with respect to the Greenwich meridian. In 1972, GMT was replaced by Coordinated Universal Time (UTC) as the international time reference. Nevertheless, UTC is colloquially referred to as GMT although this is technically not correct.

Ephemeris Time

Gmt Time In Seconds Calculator

During the 20th century, it was found that the rotational period of Earth (length of the day) was gradually slowing down.For the purposes of orbital calculations, time using Earth's rotation was abandoned for a more uniform time scale basedon Earth's orbit about the Sun. In 1952, the International Astronomical Union (IAU) introduced Ephemeris Time (ET) to address this problem. The ephemeris second was defined as a fraction of the tropical year for 1900 Jan 01, as calculated from Newcomb's tables of the Sun (1895). Ephemeris Time was used for Solar System ephemeris calculations until it was replaced by TD in 1979.

Terrestrial Dynamical Time

TD was introduced by the IAU in 1979 as the coordinate time scale for an observer on the surface of Earth. It takes into account relativistic effects and is based on International Atomic Time (TAI), which is a high-precision standard usingseveral hundred atomic clocks worldwide. As such, TD is the atomic time equivalent to its predecessor ET and is used in the theories of motion for bodies in the solar system. To ensure continuity with ET, TD was defined to match ET for the date 1977 Jan 01. In 1991, the IAU refined the definition of TD to make it more precise. It was also renamed Terrestrial Time (TT), although on this Web site, the older name Terrestrial Dynamical Time is preferred and used.

Universal Time

For many centuries, the fundamental unit of time was the rotational period of Earth with respect to the Sun. GMT was the standard time reference based on the mean solar time on the 0° longitude meridian in Greenwich, England. Universal Time (UT) is the modern counterpart to GMT and is determined from Very Long Baseline Interferometry (VLBI) observationsof the diurnal motion of quasars. Unfortunately, UT is not a uniform time scale because Earth's rotational period is (on average) gradually increasing.

The change is primarily due to tidal friction between Earth's oceans and its rocky mantle through the gravitational attractionof the Moon and, to a lesser extent, the Sun. This secular acceleration gradually transfers angular momentum from Earth to the Moon. As Earth loses energy and slows down, the Moon gains this energy and its orbital period and distance from Earth increase. Shorter period fluctuations in terrestrial rotation also exist, which can produce an accumulated clock error of ±20 s in one or more decades. These decade variations are attributed to several geophysical mechanisms including fluid interactions between the core and mantle of Earth. Climatological changes and variations in sea-level may also play significant roles because they alter Earth's moment of inertia.

The secular acceleration of the Moon implies an increase in the length of day (LOD) of about 2.3 milliseconds per century.Such a small amount may seem insignificant, but it has very measurable cumulative effects. At this rate, time as measured through Earth's rotation is losing about 84 seconds per century squared when compared to atomic time.

Coordinated Universal Time

Coordinated Universal Time (UTC) is the present day basis of all civilian time throughout the world. Derived from TAI, the length of the UTC second is defined in terms of an atomic transition of the element cesium and is accurate to approximately 1 ns (billionth of a second) per day. Because most daily life is still organized around the solar day, UTC was defined to closely parallel Universal Time. The two time systems are intrinsically incompatible, however, because UTC is uniform while UT is based on Earth's rotation, which is gradually slowing. In order to keep the two times within 0.9 s of each other, a leap second is added to UTC about once every 12 to 18 months.

Delta T (ΔT)

The orbital positions of the Sun and Moon required by eclipse predictions, are calculated using TD because it is a uniform time scale. World time zones and daily life, however, are based on UT[2]. In order to convert eclipse predictions from TD to UT, the difference between these two time scales must be known. The parameter delta-T (ΔT) is the arithmetic difference, in seconds, between the two as:

Past values of ΔT can be deduced from the historical records. In particular, hundreds of eclipse observations (both solar and lunar) were recorded in early European, Middle Eastern, and Chinese annals, manuscripts, and canons. In spite of their relatively low precision, these data represent the only evidence for the value of ΔT prior to 1600 CE. In the centuries following the introduction of the telescope (circa 1609 CE), thousands of high quality observations have been made of lunar occultations of stars. The number and accuracy of these timings increase from the 17th through the 20th century, affording valuable data in the determination of ΔT.

For more information, visit the ΔT page.

A series of polynomial expressions have been derived to simplify the evaluation of ΔT for any time during the interval -1999 to +3000. The uncertainty in ΔT over this period can be estimated from scatter in the measurements.

The information above was previously published in:

Five Millennium Canon of Lunar Eclipses: -1999 to +3000 (NASA TP-2009-214172)
Five Millennium Catalog of Lunar Eclipses: -1999 to +3000 (NASA TP-2009-214173)

Return to main index for:

Five Millennium Catalog of Lunar Eclipses


Gmt Time In Seconds Time

    [1] GMT was originally reckoned from noon to noon. In 1925, some countries shifted GMT by 12 h so that it would begin at Greenwich midnight. This new definition is the one in common usage for world time and in the navigational publications of English-speaking countries. The designation Greenwich Mean Astronomical Time (GMAT) is reserved for the reckoning of time from noon (and previously called GMT).

    [2] World time zones are actually based on Coordinated Universal Time (UTC). It is an atomic time synchronized and adjusted to stay within 0.9 seconds of astronomically determined Universal Time (UT). Occasionally, a 'leap second' is added to UTC to keep it in sync with UT (which changes due to variations in Earth's rotation rate).