Instant · Precise · Universal
28 units available
6 categories total
To convert sidereal years to days: multiply by 365.25636. To tropical years: multiply by 365.25636/365.24219.
1 sidereal year ≈ 365.25636 days ≈ 365 d 6 h 9 min 10 s. About 20 min 24 s longer than the tropical year.
For example, 1 Year (Sidereal) (yr (Sid)) = 8790.153738 Hour (Sidereal) (h (Sid)).
| Year (Sidereal) (yr (Sid)) | Hour (Sidereal) (h (Sid)) |
|---|---|
| 0.1 | 879.0153738 |
| 0.5 | 4395.076869 |
| 1 | 8790.153738 |
| 2 | 17580.30748 |
| 5 | 43950.76869 |
| 10 | 87901.53738 |
| 25 | 219753.8435 |
| 50 | 439507.6869 |
| 100 | 879015.3738 |
| 500 | 4395076.869 |
| 1000 | 8790153.738 |
The sidereal year is the time for Earth to complete one orbit relative to the fixed stars — approximately 365.25636 days (31,558,149.7632 seconds).
1 sidereal year ≈ 365.25636 days ≈ 365 d 6 h 9 min 10 s. About 20 min 24 s longer than the tropical year.
To convert sidereal years to days: multiply by 365.25636. To tropical years: multiply by 365.25636/365.24219.
Tracking stellar positions, calculating satellite orbital decay, and determining long-term star catalog corrections.
The ~20-minute difference between sidereal and tropical years is caused by axial precession — Earth's axis traces a full circle every ~25,772 years.
Using sidereal year when tropical year is intended (or vice versa) in calendar calculations.
Think of it this way: the sidereal year measures Earth's orbit relative to stars. The tropical year measures relative to seasons. Precession makes them differ.
The sidereal hour is 1/24 of a sidereal day — approximately 3,590.17 seconds (59 minutes and 50.17 seconds in solar time).
1 sidereal hour = 3,590.17 solar seconds ≈ 59 min 50.17 s in solar time. 24 sidereal hours = 1 sidereal day.
To convert sidereal hours to solar seconds: multiply by 3,590.17. To solar hours: multiply by 0.99727.
Right ascension in celestial coordinates is measured in hours (0–24 h of sidereal time), directly using sidereal hours.
Right ascension is measured in hours: 1 h of RA = 15° of sky. The entire sky is 24 sidereal hours in rotation.
Treating sidereal hours as exactly 60 solar minutes. The ~10-second difference matters for precision tracking.
If you use a star-tracking telescope, it rotates once per sidereal day (23h 56m). Each sidereal hour, it covers 15° of sky.



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