Time standard
Coordinated 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.
- Type
- Time standard
- Domain
- Scientific connections
- Connections
- 5
- 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 International Atomic Time (TAI).
- 04
Connect
5 graph relations shape the knowledge viewport.
- Object type
- Time standard
- Graph relations
- 5
- Verified sources
- 1
- Image records
- 0
- Domain
- Scientific connections
- Status
- Graph entity
Scientific map
Atlas context
- Associated with
International Atomic Time (TAI)
- Associated with
Deep Space Network (DSN)
- Associated with
Universal Time (UT1)
- Associated with
The Leap Second
Original SVG diagram
Scientific schematic
- Object class
- Time standard
- Catalog numbers
- Not recorded
- Graph relations
- 5
- 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 withDeep Space Network (DSN)
- Associated withInternational Atomic Time (TAI)
- Associated withJulian Date
- Associated withThe Leap Second
- Associated withUniversal Time (UT1)
Continue the atlas
Curated next objects
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.
tracking networkDeep Space Network (DSN)
NASA's international array of giant radio antennas — at Goldstone (California), Madrid, and Canberra — that communicates with interplanetary spacecraft and distant satellites, spaced around the globe for continuous coverage.
time standardUniversal Time (UT1)
The form of Universal Time tied to the actual rotation of the Earth, measured from the positions of distant sources. Because the Earth's spin is slightly irregular and slowly slowing, UT1 drifts against the steady beat of atomic time.
time standardThe Leap Second
The extra second occasionally inserted into Coordinated Universal Time to keep it within 0.9 seconds of UT1, so that civil clocks stay in step with the turning of the Earth. As atomic time and Earth rotation drift apart, leap seconds bridge the gap — a practice now being reconsidered.
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.
time standardSidereal Time
Time kept by the stars rather than the Sun — it measures the Earth's rotation relative to the fixed sky. A sidereal day is about four minutes shorter than a solar day, because the Earth must turn a little further each day to face the Sun again as it moves along its orbit.
Data
Scientific data & provenance
Data & provenance
- Stable ID
time_standard:utc- Type
- Time standard
- Domain
- Scientific connections
- Relationships
- 5
- 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:utc
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 standardSidereal TimeLinked through Universal Time (UT1)
- Time standardTerrestrial TimeLinked through International Atomic Time (TAI)
- OrganizationInternational Earth Rotation and Reference Systems Service (IERS)Linked through Universal Time (UT1)
- Time standardGPS TimeLinked through International Atomic Time (TAI)
- Time standardSpacecraft Clock (SCLK)Linked through Deep Space Network (DSN)
- Tracking stationCanberra Deep Space Communication ComplexLinked through Deep Space Network (DSN)
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.