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.

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 $\frac{1}{3}$ nanosecond.

A flick is defined as $\frac{1}{705600}$ millisecond.

A shake is defined as $1.\times {10}^{\mathrm{-8}}$ second.

A svedberg is defined as $1.\times {10}^{\mathrm{-13}}$ second.

A blink is defined as $0.00001$ day.

An SI minute is defined as $60$ seconds.

An SI hour is defined as $60$ minutes.

An SI day is defined as $24$ hours.

A sidereal day, which varies daily, is approximately $23$ hours, $56$ minutes, and $4.1$ seconds.

The sidereal hour, minute and second are defined as fractions of the sidereal day with factors of $\frac{1}{24}$, $\frac{1}{1440}$, and $0.00001157407407$, respectively.

A standard pentad is defined as $5$ days.

A standard week is defined as $7$ days.

A standard fortnight is defined as $14$ days.

A planck time is defined as the square root of: the planck constant times the Newtonian gravitational constant, divided by twice $\mathrm{\pi }$ times the speed of light to the fifth power.

$\mathrm{convert}\left('s'\,'\mathrm{dimensions}'\,'\mathrm{base}'=\mathrm{true}\right)$

$\mathrm{time}$

$\mathrm{convert}\left(1.0\,'\mathrm{units}'\,'\mathrm{year}\left[\mathrm{tropical}\right]'\,'\mathrm{year}\left[\mathrm{standard}\right]'\right)$

$1.000663534$

$\mathrm{convert}\left(1.0\,'\mathrm{units}'\,'\mathrm{year}\left[\mathrm{tropical}\right]'\,'\mathrm{year}\left[\mathrm{Julian}\right]'\right)$

$0.9999786175$

$\mathrm{convert}\left(1.0\,'\mathrm{units}'\,'\mathrm{year}\left[\mathrm{tropical}\right]'\,'\mathrm{year}\left[\mathrm{Gregorian}\right]'\right)$

$0.9999991514$

$\mathrm{convert}\left(1.0\,'\mathrm{units}'\,'\mathrm{year}\left[\mathrm{tropical}\right]'\,'\mathrm{year}\left[\mathrm{Orthodox}\right]'\right)$

$0.9999999119$

$\mathrm{convert}\left(1.0\,'\mathrm{units}'\,'\mathrm{year}\left[\mathrm{tropical}\right]'\,'\mathrm{year}\left[\mathrm{sidereal}\right]'\right)$

$0.9999611973$

$\mathrm{convert}\left(1\,'\mathrm{units}'\,\frac{'\mathrm{centimeters}'}{'\mathrm{minute}'}\,\frac{'\mathrm{furlong}'}{'\mathrm{fortnight}'}\right)$

$\frac{1400}{1397}$

$\mathrm{evalf}\left(\right)$

$1.002147459$