Day (Sidereal) to Month (Synodic) Converter
Unit Converter
Instant · Precise · Universal
28 units available
6 categories total
How to Convert Day (Sidereal) to Month (Synodic)
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)) = 0.03377072947 Month (Synodic) (mo (syn)).
Day (Sidereal) to Month (Synodic) — Common Values
| Day (Sidereal) (d (Sid)) | Month (Synodic) (mo (syn)) |
|---|---|
| 0.1 | 0.003377072947 |
| 0.5 | 0.01688536473 |
| 1 | 0.03377072947 |
| 2 | 0.06754145894 |
| 5 | 0.1688536473 |
| 10 | 0.3377072947 |
| 25 | 0.8442682367 |
| 50 | 1.688536473 |
| 100 | 3.377072947 |
| 500 | 16.88536473 |
| 1000 | 33.77072947 |
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 Month (Synodic) (mo (syn))
Definition
The synodic month is the time between two successive new moons — approximately 29.53059 days (2,551,442.976 seconds).
Mathematical Relationship
1 synodic month ≈ 29.53059 days ≈ 708.73 hours. Longer than a sidereal month (27.32 days) because Earth also moves in its orbit.
Conversion Formula
To convert synodic months to days: multiply by 29.53059. To convert to calendar months: multiply by ~0.970.
Practical Applications
Islamic calendar months, tidal cycle predictions, menstrual cycle correlations, and astronomical event planning.
Interesting Facts
The synodic month is ~2.2 days longer than the sidereal month because the Moon must 'catch up' to the same Sun-Earth-Moon alignment as Earth orbits.
Common Mistakes
Confusing synodic month with calendar month. The synodic month is ~29.5 days, shorter than most calendar months.
Educational Tips
Watch the Moon for a full cycle from new moon to new moon — that's one synodic month (~29.5 days).