Astronomical Unit Calculator
Convert between astronomical units and other length measurements for space distances
Convert Astronomical Units
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Conversion Result
Conversion factor: 1 au = 149,597,870,700 m (IAU 2012 definition)
Calculation: 0 au × conversion factor = 0 km
Quick Reference: 1 Astronomical Unit =
Common Space Distance Examples
Earth's Orbital Distance
Average distance from Sun: 1.00 au (by definition)
Perihelion (closest): 0.983 au (January)
Aphelion (farthest): 1.017 au (July)
Mars Distance
Closest approach: 0.37 au (55.3 million km)
Average distance: 1.52 au (227.9 million km)
Farthest distance: 2.67 au (401 million km)
Jupiter Distance
Average distance: 5.2 au (778 million km)
Light travel time: About 43 minutes from Earth
Solar System Distances (AU)
Astronomy Facts
Light from the Sun takes 8 minutes 20 seconds to reach Earth
The nearest star (Proxima Centauri) is 268,552 au away
1 parsec equals 206,265 astronomical units
AU is perfect for measuring interplanetary distances
Understanding the Astronomical Unit
What is an Astronomical Unit?
An astronomical unit (au) is a unit of length used primarily in astronomy to measure distances within our solar system. It represents the average distance between Earth and the Sun, making it a natural and convenient unit for expressing interplanetary distances.
IAU 2012 Definition
1 au = 149,597,870,700 meters
The International Astronomical Union (IAU) established this exact value in 2012, providing a precise and unchanging standard for astronomical measurements.
Historical Development
The concept of the astronomical unit has been refined over centuries. Early astronomers used parallax measurements and geometric calculations to estimate the Earth-Sun distance. Modern techniques including radar and spacecraft telemetry have provided the precision needed for today's exact definition.
Why Use Astronomical Units?
- •Makes solar system distances more manageable
- •Provides intuitive scale relative to Earth's orbit
- •Standard unit in planetary astronomy
- •Connects to other astronomical units like parsecs