Units of Time
Description
Examples
Time is a base dimension in the International System of Units. The SI unit of time is the second, defined as the time interval equal to 9192631770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium-133 atom (13th CGPM, 1967).
Maple knows the units of time listed in the following table.
Name
Symbols
Context
Alternate Spellings
Prefixes
wink
standard *
winks
flick
time
flicks
SI
shake
shakes
svedberg
svedbergs
blink
blinks
second
s
SI *
seconds
sidereal
Atomic
minute
min
minutes
hour
h
hours
day
d
days
pentad
pentads
week
wk
weeks
fortnight
month
mo
lunar *
months
anomalistic
nodical
lune
lunes
lunour
lunours
year
yr
tropical *
years
ellipse
standard
leap
Julian
Gregorian
Orthodox
galactic
biennium
biennia
triennium
triennia
quadrennium
quadrennia
quinquennium
quinquennia
decade
decades
century
centuries
millennium
millennia
eon
eons, aeon, aeons
planck_time
planck *
planck_times
An asterisk ( * ) indicates the default context, an at sign (@) indicates an abbreviation, and under the prefixes column, SI indicates that the unit takes all SI prefixes, IEC indicates that the unit takes IEC prefixes, and SI+ and SI- indicate that the unit takes only positive and negative SI prefixes, respectively. Refer to a unit in the Units package by indexing the name or symbol with the context, for example, second[SI] or h[SI]; or, if the context is indicated as the default, by using only the unit name or symbol, for example, second or h.
The units of time are defined as follows. Unless otherwise stated, conversions refer to SI units.
A wink is defined as 13nanosecond.
A flick is defined as 1705600millisecond.
A shake is defined as 1.×10−8second.
A svedberg is defined as 1.×10−13second.
A blink is defined as 0.00001day.
An SI minute is defined as 60seconds.
An SI hour is defined as 60minutes.
An SI day is defined as 24hours.
A sidereal day, which varies daily, is approximately 23hours, 56minutes, and 4.1seconds.
The sidereal hour, minute and second are defined as fractions of the sidereal day with factors of 124, 11440, and 0.00001157407407, respectively.
A standard pentad is defined as 5days.
A standard week is defined as 7days.
A standard fortnight is defined as 14days.
A planck time is defined as the square root of: the planck constant times the Newtonian gravitational constant, divided by twice π times the speed of light to the fifth power.
The Month
A lunar month, which has also been called the lunation and synodic month, is approximately 29days, 12hours, 44minutes, and 2.8seconds.
A lune is defined as 130lunar month.
A lunour is defined as 124lunar day.
A nodical month, which has also been called the dracontic month, is approximately 27days, 5hours, 5minutes, and 35.8seconds.
An anomalistic month is approximately 27days, 13hours, 18minutes, and 33.1seconds.
A sidereal month is approximately 27days, 7hours, 43minutes, and 11.6seconds.
The Year
A standard year is defined as 365days.
A leap year is defined as 366days.
A sidereal year is approximately 365days, 6hours, 9minutes, and 9.7632seconds.
An ellipse year is approximately 365days, 14hours, 52minutes, and 54.48seconds.
A tropical year is approximately 365days, 5hours, 48minutes, and 45.216seconds.
An anomalistic year is approximately 365days, 6hours, 13minutes, and 52.464seconds.
The Julian calendar includes a leap year every fourth year. Therefore, a Julian year is defined as 365.25days.
The Gregorian calendar includes a leap year every fourth year unless the year is a multiple of 100 and not a multiple of 400. Therefore, a Gregorian year is defined as 365.2425days.
The proposed Orthodox calendar includes a leap year every fourth year, leaving out 7 leap years every 900 years. Therefore, a Orthodox year is defined as 366.2424222...days.
A galactic year is approximately 2.25×108years.
Multiple Years
For the following units the Gregorian context is based on the Gregorian year and the tropical context is based on the tropical year. An exception is the eon, which has only a tropical context that is based on the tropical year.
A biennium is defined as 2years.
A triennium is defined as 3years.
A quadrennium is defined as 4years.
A quinquennium is defined as 5years.
A decade is defined as 10years.
A century is defined as 100years.
A millennium is defined as 1000years.
An eon is defined as 1.×109years.
convert⁡s,dimensions,base=true
convert⁡1.0,units,yeartropical,yearstandard
1.000663534
convert⁡1.0,units,yeartropical,yearJulian
0.9999786175
convert⁡1.0,units,yeartropical,yearGregorian
0.9999991514
convert⁡1.0,units,yeartropical,yearOrthodox
0.9999999119
convert⁡1.0,units,yeartropical,yearsidereal
0.9999611973
convert⁡1,units,centimetersminute,furlongfortnight
14001397
evalf⁡
1.002147459
See Also
convert/dimensions
convert/units
evalf
Units
Units/Index
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