Time standard
International Atomic Time (TAI)
A continuous atomic timescale kept by hundreds of atomic clocks worldwide — the stable foundation from which civil time is derived. TAI never inserts leap seconds, making it ideal for measuring precise intervals.
- Type
- Time standard
- Domain
- Scientific connections
- Connections
- 4
- Type: Time standard
- Domain: Scientific connections
Experience system V6
Time standard scientific profile
A graph-grounded scientific layout that adapts to available evidence, imagery, relations, and source coverage.
- 01
Observe
The page falls back to graph and source evidence when no cleared image is available.
- 02
Measure
Measurement panels use graph coverage, catalog identifiers, and source availability without inventing values.
- 03
Locate
Associated with Deep Space Atomic Clock.
- 04
Connect
4 graph relations shape the knowledge viewport.
- Object type
- Time standard
- Graph relations
- 4
- Verified sources
- 1
- Image records
- 0
- Domain
- Scientific connections
- Status
- Graph entity
Scientific map
Atlas context
- Associated with
Deep Space Atomic Clock
- Associated with
Coordinated Universal Time (UTC)
- Associated with
GPS Time
- Associated with
Terrestrial Time
Original SVG diagram
Scientific schematic
- Object class
- Time standard
- Catalog numbers
- Not recorded
- Graph relations
- 4
- Sources
- 1
Visual knowledge graph
Relationships, not isolated facts
This viewport is generated from the Asteria knowledge graph. Science, culture, and interpretive links remain separated by domain so visual context never changes the evidentiary meaning of a relation.
- Associated withCoordinated Universal Time (UTC)
- Associated withDeep Space Atomic Clock
- Associated withGPS Time
- Associated withTerrestrial Time
Continue the atlas
Curated next objects
Deep Space Atomic Clock
A miniaturised, ultra-stable atomic clock small enough to fly on a spacecraft. By putting precise timekeeping onboard, it enables one-way radiometric navigation — the spacecraft can determine its own position without the round-trip to a ground clock — a technology demonstrated in Earth orbit.
time standardCoordinated Universal Time (UTC)
The civil time standard, derived from International Atomic Time but kept within a second of the Earth's rotation by occasional leap seconds. Deep-space tracking tags its measurements in UTC.
time standardGPS Time
The continuous timescale of the Global Positioning System, offset from TAI by a fixed number of seconds and widely used to synchronise ground equipment.
time standardTerrestrial Time
The idealised time on the Earth's surface used as the time axis for astronomical events and geocentric ephemerides. It runs at the same rate as International Atomic Time but is offset ahead of it by a fixed 32.184 seconds, for continuity with the older ephemeris time.
time standardJulian Date
A continuous count of days (and fractions) since noon Universal Time on 1 January 4713 BC in the proleptic Julian calendar, used throughout astronomy to timestamp observations without the awkwardness of calendar months and leap years. The Modified Julian Date (MJD = JD − 2400000.5) shifts the origin to a recent midnight for convenience.
reference frameThe J2000 Epoch
The standard reference epoch of modern astronomy — noon on 1 January 2000, in Terrestrial Time. Because the sky's apparent frame drifts with precession, coordinates and orbital elements are stated for a fixed epoch, and J2000.0 is the one in near-universal use.
Data
Scientific data & provenance
Data & provenance
- Stable ID
time_standard:tai- Type
- Time standard
- Domain
- Scientific connections
- Relationships
- 4
- Graph version
- 1.0.0
Dataset membership
Open data
In the graph export: graph.json · graph.jsonld
Planned API: GET /api/v0/entities/time_standard:tai
Scientific quality
Substantial2 of 4 applicable dimensions complete, 1 partial
- Description
- Complete
- Source coverage
- Partial
- Relationship coverage
- Complete
- Review coverage
- None
- Citation coverage
- Not applicable
- Image coverage
- Not applicable
- Timeline coverage
- Not applicable
Scientific entity. Dimensions that cannot apply to this object are excluded rather than counted as gaps. See the evidence framework and authority dashboard.
You might also explore
- Time standardJulian DateLinked through Coordinated Universal Time (UTC)
- Reference frameThe J2000 EpochLinked through Terrestrial Time
- Time standardBarycentric Dynamical TimeLinked through Terrestrial Time
- Time standardThe Leap SecondLinked through Coordinated Universal Time (UTC)
- Time standardUniversal Time (UT1)Linked through Coordinated Universal Time (UTC)
- Tracking networkDeep Space Network (DSN)Linked through Coordinated Universal Time (UTC)
Sources & references
The primary and reference sources this topic draws on.
- NASANational Aeronautics and Space Administration
Mission data, planetary science, space telescopes, and public-domain imagery.
Most NASA-produced imagery is in the public domain; individual items are checked for usage terms before publication.