Day (Sidereal) to Hour (Sidereal) Converter
Unit Converter
Instant · Precise · Universal
28 units available
6 categories total
How to Convert Day (Sidereal) to Hour (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)) = 24.00000025 Hour (Sidereal) (h (Sid)).
Day (Sidereal) to Hour (Sidereal) — Common Values
| Day (Sidereal) (d (Sid)) | Hour (Sidereal) (h (Sid)) |
|---|---|
| 0.1 | 2.400000025 |
| 0.5 | 12.00000013 |
| 1 | 24.00000025 |
| 2 | 48.0000005 |
| 5 | 120.0000013 |
| 10 | 240.0000025 |
| 25 | 600.0000063 |
| 50 | 1200.000013 |
| 100 | 2400.000025 |
| 500 | 12000.00013 |
| 1000 | 24000.00025 |
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 Hour (Sidereal) (h (Sid))
Definition
The sidereal hour is 1/24 of a sidereal day — approximately 3,590.17 seconds (59 minutes and 50.17 seconds in solar time).
Mathematical Relationship
1 sidereal hour = 3,590.17 solar seconds ≈ 59 min 50.17 s in solar time. 24 sidereal hours = 1 sidereal day.
Conversion Formula
To convert sidereal hours to solar seconds: multiply by 3,590.17. To solar hours: multiply by 0.99727.
Practical Applications
Right ascension in celestial coordinates is measured in hours (0–24 h of sidereal time), directly using sidereal hours.
Interesting Facts
Right ascension is measured in hours: 1 h of RA = 15° of sky. The entire sky is 24 sidereal hours in rotation.
Common Mistakes
Treating sidereal hours as exactly 60 solar minutes. The ~10-second difference matters for precision tracking.
Educational Tips
If you use a star-tracking telescope, it rotates once per sidereal day (23h 56m). Each sidereal hour, it covers 15° of sky.