Seconds to Lustra (s to lustrum)
1 second equals 6.337747701×10⁻⁹ lustra (rounded).
How to convert seconds to lustra
To convert seconds to lustra, multiply the number of seconds by 6.337747701×10⁻⁹. The factor is rounded to 10 significant digits. To go the other way, multiply lustra by 157,784,760.
lustra = seconds × 6.337747701×10⁻⁹
Example: 10 seconds = 6.337747701×10⁻⁸ lustra.
Months and years are not constant. This site uses the average Gregorian year of 365.2425 days, so one 'year' converts to 365.2425 days, not 365; use 'common year' for exactly 365 days.
About these units
Second (s)
The SI base unit of time, defined by the radiation frequency of the cesium-133 atom: 9,192,631,770 cycles per second.
Our word second is a leftover of Latin. Medieval scholars divided a degree, and later the hour, into 60 parts called pars minuta prima, the first small part, and divided those again into pars minuta secunda, the second small part. NIST traces the roots further back: Babylonian and Greek astronomers split the circle into 360 degrees, and around 150 C.E. Ptolemy split each degree into 60 minutes and each minute into 60 seconds. Clocks that could show seconds appeared only in the later 16th century, and Christiaan Huygens's pendulum clock of 1656 was the first able to keep time accurately to the second.
For most of history the second was a fraction of a day, and in 1956 it was redefined as a fraction of the tropical year, a definition the SI took over in 1960. In 1967 the 13th CGPM switched to atoms: 9,192,631,770 periods of the radiation tied to a hyperfine transition of caesium-133. The 2019 SI revision restated this by fixing the caesium frequency at 9,192,631,770 hertz. NIST reports that commercial caesium clocks stay within about a three-millionth of a second per year, and experimental clocks based on other atoms are roughly ten thousand times more precise.
The second is the reference unit for time on this site.
Sources: NIST: the second and the SI redefinition; BIPM: SI Brochure, 9th edition; Wikipedia: Second
Lustrum (lustrum)
Five years, the interval between Roman censuses and the ritual purification that closed each one.
Roman censors counted citizens and their property about every five years, and the period between counts took the name lustrum. The word is tied to a Latin verb for purifying, because each census ended with a solemn purification of the people, often performed through the sacrifice of a bull, a ram and a pig in the Campus Martius. Ancient tradition credited the first one to King Servius Tullius in 566 BC.
Censors held office from 443 BC, and a later law cut their term from a full lustrum to 18 months. The interval was not always kept: Livy recorded only 21 lustra between 443 BC and 294 BC where 30 might have been expected, and some censuses took place without the ritual. The last censors were appointed in 23 BC under Augustus. In modern English the word survives for any five-year span. Using a Gregorian year of 365.2425 days, one lustrum is about 157.8 million seconds, which is the figure used here.
1 lustrum = 157,784,760 seconds (exactly).
Sources: Wikipedia: Lustrum; Wikipedia: Roman census
Related conversions
- Lustra to seconds (reverse)
- Seconds to minutes
- Seconds to hours
- Seconds to days
- Seconds to weeks
- Seconds to months
- Seconds to years
- Seconds to milliseconds
- Seconds to microseconds
- Seconds to nanoseconds
- Seconds to decades
- Seconds to centuries
- Seconds to millennia
- Minutes to lustra
- Hours to lustra
- Days to lustra
- Weeks to lustra
- Months to lustra
- Years to lustra
See all time units.