{
  "name": "One nanosecond, compared",
  "desc": "A light-nanosecond against the international foot; cesium periods in a nanosecond; a 3 GHz clock tick; light crossing times for an inch, foot, yard, meter, kilometer and mile; rounded rules of thumb for the speed of light and how far off they are; the light time for 1 astronomical unit. One comparison per row, with its method and qualifier.",
  "lic": "CC BY 4.0",
  "lic_url": "https://creativecommons.org/licenses/by/4.0/",
  "by": "The Yardstick Almanac",
  "url": "https://theyardstickalmanac.com/scale/grace-hopper-nanosecond/",
  "from": [
    "BIPM, The International System of Units (SI Brochure), 9th edition, V4.01 (June 2026): defining values of c and the cesium frequency, SI prefixes (Table 7)",
    "BIPM, SI Brochure, 9th edition, V4.01, Table 8 and note (j): 1 au = 149,597,870,700 m (IAU 2012 Resolution B2)",
    "NIST Handbook 44-2026, Appendix C: 1 inch = 2.54 cm, 1 foot = 0.3048 m, 1 yard = 0.9144 m, 1 mile = 1.609344 km, exactly (24 FR 5348, 1959)"
  ],
  "how": "Compiled by The Yardstick Almanac from the data listed",
  "data_by": [
    "Defined values from the BIPM SI Brochure, 9th ed. V4.01 (CC BY 4.0; adapted: values used in new calculations) and NIST Handbook 44-2026, Appendix C; computed 2026-11-01, CC BY 4.0"
  ]
}