sidereal day
The sidereal day is one rotation of the Earth measured against the fixed stars rather than against the sun: 86,164.0905 seconds, about three minutes and fifty-six seconds short of the civil day. The difference exists because the Earth also moves along its orbit during a rotation, so it must turn slightly further than 360° to bring the sun back to the same place in the sky.
| 1 | 86,164.091 |
Where the unit came from
Telescope drives are geared to sidereal rate, not solar, which is why a star tracked without correction stays put and the sun does not. The shortfall accumulates to exactly one extra rotation over a year, so a year holds one more sidereal day than civil days.
One sidereal day in every time unit
| 1.59822e+48 | Planck time (tP) | |
| 8.61641e+22 | attosecond (as) | |
| 8.61641e+19 | femtosecond (fs) | |
| 8.61641e+16 | picosecond (ps) | |
| 86,164,100,000,000 | nanosecond (ns) | |
| 8,616,410,000,000 | shake (shake) | |
| 86,164,100,000 | microsecond (µs) | |
| 86,164,100 | millisecond (ms) | |
| 86,164.1 | second (s) | |
| 1,436.07 | minute (min) | |
| 23.9345 | hour (h) | |
| 1 | sidereal day (sd)this unit | |
| 0.99727 | day (d) | |
| 0.142467 | week (wk) | |
| 0.0712335 | fortnight (fn) | |
| 0.0327652 | month (mo) | |
| 0.00273038 | year (yr) | |
| 0.000273038 | decade (dec) | |
| 0.0000273038 | century (cent) | |
| 0.00000273038 | millennium (mil) | |
| 2.73038e-09 | megayear (Myr) | |
| 2.73038e-12 | eon (eon) |
Solvers that use time