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)) = 26.08974021 Fortnight (fn).
| Year (Sidereal) (yr (Sid)) | Fortnight (fn) |
|---|---|
| 0.1 | 2.608974021 |
| 0.5 | 13.04487011 |
| 1 | 26.08974021 |
| 2 | 52.17948043 |
| 5 | 130.4487011 |
| 10 | 260.8974021 |
| 25 | 652.2435054 |
| 50 | 1304.487011 |
| 100 | 2608.974021 |
| 500 | 13044.87011 |
| 1000 | 26089.74021 |
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.
A fortnight is a unit of time equal to 14 days, or two weeks (1,209,600 seconds).
1 fortnight = 14 d = 2 wk = 336 h = 1,209,600 s.
To convert fortnights to days: multiply by 14. To convert fortnights to weeks: multiply by 2.
Fortnightly pay cycles (common in Australia and UK), rental payment periods, and magazine publication schedules.
In Australia, being paid 'fortnightly' is the most common pay cycle. The FFF system defines speed in furlongs per fortnight.
Americans may be unfamiliar with the term. In US English, 'two weeks' is the standard equivalent.
Fortnight = fourteen nights. In countries where it's common, it's as natural as saying 'week' — just meaning two of them.



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