Day (Sidereal) to Second (Sidereal) Converter
Unit Converter
Instant · Precise · Universal
28 units available
6 categories total
How to Convert Day (Sidereal) to Second (Sidereal)
To convert sidereal days to solar days: multiply by 0.99727. To hours: multiply by 23.9345.
1 sidereal day ≈ 23 h 56 min 4.09 s = 86,164.09 s. About 3 min 56 s shorter than a solar day.
For example, 1 Day (Sidereal) (d (Sid)) = 86399.99705 Second (Sidereal) (s (Sid)).
Day (Sidereal) to Second (Sidereal) — Common Values
| Day (Sidereal) (d (Sid)) | Second (Sidereal) (s (Sid)) |
|---|---|
| 0.1 | 8639.999705 |
| 0.5 | 43199.99853 |
| 1 | 86399.99705 |
| 2 | 172799.9941 |
| 5 | 431999.9853 |
| 10 | 863999.9705 |
| 25 | 2159999.926 |
| 50 | 4319999.853 |
| 100 | 8639999.705 |
| 500 | 43199998.53 |
| 1000 | 86399997.05 |
About Day (Sidereal) (d (Sid))
Definition
The sidereal day is the time for Earth to rotate once relative to distant stars — approximately 23 hours, 56 minutes, and 4 seconds (86,164.0905 seconds).
Mathematical Relationship
1 sidereal day ≈ 23 h 56 min 4.09 s = 86,164.09 s. About 3 min 56 s shorter than a solar day.
Conversion Formula
To convert sidereal days to solar days: multiply by 0.99727. To hours: multiply by 23.9345.
Practical Applications
Telescope pointing and tracking, satellite ground track calculations, and astronomical observation scheduling.
Interesting Facts
Because of the ~4-minute difference, the night sky shifts gradually — the same star appears at the same position about 4 minutes earlier each night.
Common Mistakes
Equating sidereal day with solar day. The ~4-minute difference accumulates — after 6 months, sidereal noon is at solar midnight.
Educational Tips
Imagine Earth spinning AND orbiting: after one full spin (sidereal day), Earth has moved in its orbit, so the Sun hasn't quite returned to the same position — that takes ~4 more minutes.
About Second (Sidereal) (s (Sid))
Definition
The sidereal second is 1/60 of a sidereal minute — approximately 0.99727 solar seconds.
Mathematical Relationship
1 sidereal second ≈ 0.99727 solar seconds. 86,400 sidereal seconds = 1 sidereal day.
Conversion Formula
To convert sidereal seconds to solar seconds: multiply by 0.99727. One solar second ≈ 1.00274 sidereal seconds.
Practical Applications
Telescope tracking motors rotate at sidereal rate (1 revolution per sidereal day) to follow stars across the sky.
Interesting Facts
The difference between sidereal and solar seconds (2.73 ms) seems tiny, but over a day it adds up to the full ~236 s difference.
Common Mistakes
Assuming sidereal seconds equal solar seconds. The ~0.27% difference is critical in precision astronomy.
Educational Tips
Multiply any sidereal time interval by 0.99727 to get the solar equivalent. This ratio stays constant at all time scales.