Astronomical Unit Converter Formula
Understand the math behind the astronomical unit converter. Each variable explained with a worked example.
Formulas Used
Kilometres
km = au * 149597870.7Miles
miles = au * 92955807.3Light-Minutes
light_minutes = au * 8.3167Variables
| Variable | Description | Default |
|---|---|---|
au | Distance(AU) | 1 |
How It Works
The Astronomical Unit
1 AU = 149 597 870.7 km (exact, IAU 2012)
Light takes about 8.317 minutes to travel 1 AU. The AU is the fundamental baseline for solar system distances.
Worked Example
Jupiter orbits at about 5.2 AU.
au = 5.2
- 01km = 5.2 × 149 597 870.7 ≈ 778 million km
- 02Light-minutes = 5.2 × 8.317 = 43.2
- 03Light takes about 43 minutes to reach Jupiter from the Sun.
Frequently Asked Questions
How was the AU originally measured?
Through transits of Venus and radar ranging. Since 2012 the IAU defines it as exactly 149 597 870 700 m.
How many AU to the nearest star?
Proxima Centauri is about 268 000 AU away.
What is 1 AU in light-time?
Light takes 499.0 seconds (8 min 19 s) to travel 1 AU.
Ready to run the numbers?
Open Astronomical Unit Converter