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To convert fs to seconds: multiply by 10⁻¹⁵. To convert fs to picoseconds: divide by 1,000.
1 fs = 10⁻¹⁵ s = 0.001 ps = 1,000 as. Light travels about 0.3 µm in one femtosecond.
For example, 1 Femtosecond (fs) = 3.168754e-23 Year (Sidereal) (yr (Sid)).
| Femtosecond (fs) | Year (Sidereal) (yr (Sid)) |
|---|---|
| 0.1 | 3.168754e-24 |
| 0.5 | 1.584377e-23 |
| 1 | 3.168754e-23 |
| 2 | 6.337507e-23 |
| 5 | 1.584377e-22 |
| 10 | 3.168754e-22 |
| 25 | 7.921884e-22 |
| 50 | 1.584377e-21 |
| 100 | 3.168754e-21 |
| 500 | 1.584377e-20 |
| 1000 | 3.168754e-20 |
The femtosecond is a unit of time equal to 10⁻¹⁵ seconds — one quadrillionth of a second.
1 fs = 10⁻¹⁵ s = 0.001 ps = 1,000 as. Light travels about 0.3 µm in one femtosecond.
To convert fs to seconds: multiply by 10⁻¹⁵. To convert fs to picoseconds: divide by 1,000.
LASIK eye surgery uses femtosecond lasers. Also used in precision micro-machining and optical frequency combs.
A femtosecond is to one second as one second is to about 31.7 million years. The fastest chemical reactions occur on femtosecond timescales.
Confusing femtoseconds with picoseconds. Remember: fs is 1,000× shorter than ps.
Ahmed Zewail's Nobel-winning work proved we can 'photograph' chemical reactions happening in femtoseconds using ultrafast laser pulses.
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.



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