Units

Second

Citation Formats

General Reference

Science Atlas. "Second." Accessed August 30, 2026. https://science.interactiveatlas.org/units/second-unit.

APA Style

Science Atlas. (n.d.). Second. Retrieved August 30, 2026, from https://science.interactiveatlas.org/units/second-unit

BibTeX

@misc{scienceatlas-second,
  author = {Science Atlas},
  title = {Second},
  year = {2026},
  url = {https://science.interactiveatlas.org/units/second-unit},
  note = {Accessed August 30, 2026}
}

The second is the base unit of time in the International System of Units, and the one every other base unit's modern definition is now built on top of. It is defined as the duration of 9,192,631,770 cycles of the radiation given off by a caesium-133 atom switching between two specific energy states, a fixed atomic property that a caesium clock can reproduce anywhere with extreme precision, far steadier than any earlier standard based on the length of a day or a year.

Facts

Symbolthe subject's own account

s 1

Sources

1. International System of Units (Wikipedia)

WikipediaView the Source

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