Astronomical Unit Conversion Tool - Convert AU to Any Unit

Convert Astronomical Units to Other Units

Result

Quick Conversions

Auto

Convert Other Units to Astronomical Units

Result

Quick Conversions

Auto

Related Astronomical Distance Units

Light-year (ly)

Distance light travels in one year - approximately 63,241 AU

Parsec (pc)

Parallax of one arcsecond - approximately 206,265 AU

Kiloparsec (kpc)

1,000 parsecs - used for distances within galaxies

Megaparsec (Mpc)

1,000,000 parsecs - used for intergalactic distances

Astronomical Unit Conversion Table

This comprehensive AU conversion table shows how astronomical units relate to other common distance units. Use this reference for quick conversions between AU and other astronomical or terrestrial units.

Conversion To Unit Multiplier
AU to kilometers Kilometers 149,597,870.7
AU to meters Meters 149,597,870,700
AU to centimeters Centimeters 14,959,787,070,000
AU to millimeters Millimeters 149,597,870,700,000
AU to micrometers Micrometers 1.495978707e+17
AU to nanometers Nanometers 1.495978707e+20
AU to picometers Picometers 1.495978707e+23
AU to angstroms Angstroms 1.495978707e+21
AU to inches Inches 5,889,679,949,000
AU to feet Feet 490,806,662,400
AU to yards Yards 163,602,220,800
AU to miles Miles 92,955,807.3
AU to nautical miles Nautical Miles 80,776,388.1
AU to fathoms Fathoms 81,801,110,400
AU to furlongs Furlongs 743,646,458
AU to rods Rods 29,745,858,300
AU to chains Chains 7,436,464,580
AU to leagues Leagues 30,985,269.1
AU to light-years Light-years 0.0000158125
AU to parsecs Parsecs 0.00000484814
AU to kiloparsecs Kiloparsecs 4.84814e-9
AU to megaparsecs Megaparsecs 4.84814e-12
AU to planck lengths Planck Lengths 9.25779e+36

This astronomical unit conversion reference table provides accurate conversion factors for both astronomical and terrestrial units. All values are based on internationally recognized standards for maximum precision in astronomical and scientific applications.

What is an Astronomical Unit?

The astronomical unit (symbol: AU) is a unit of length used primarily for measuring distances within our solar system. It is defined as exactly 149,597,870.7 kilometers, which is approximately the average distance from the Earth to the Sun. This definition was adopted by the International Astronomical Union in 2012, fixing the value and making it independent of the Earth's actual orbital distance.

The AU provides a convenient scale for expressing planetary distances and other astronomical measurements within our solar system. Our astronomical unit conversion tool helps you easily convert between AU and other units. For example, 1 AU equals approximately 93 million miles or 150 million kilometers.

What is the SI of Astronomical Unit?

The astronomical unit is not an SI unit, but it is accepted for use with the SI. It is defined in terms of meters, which is the SI base unit for length. The relationship is fixed at exactly 1 AU = 149,597,870,700 meters. This definition ensures that all astronomical distance conversions involving AU are precise:

  • 1 AU = 149,597,870.7 kilometers
  • 1 AU = 149,597,870,700 meters
  • 1 AU = 92,955,807.3 miles
  • 1 AU = 490,806,662,400 feet

What are Astronomical Units Used For?

Astronomical units are primarily used in astronomy and astrophysics to express distances within our solar system and other stellar systems. As a standardized unit, AU provides a convenient scale for astronomical measurements:

Solar System Distances

Measuring planetary orbits, distances between planets, and spacecraft trajectories. For example, Mars is approximately 1.5 AU from the Sun, while Neptune is about 30 AU from the Sun.

Astronomical Research

Calculating orbital mechanics, gravitational interactions, and celestial mechanics. For example, determining that the distance to the nearest star (Proxima Centauri) is about 268,000 AU.

Educational Purposes

Teaching planetary science and astronomy concepts with relatable scales. For example, explaining that the Kuiper Belt extends from about 30 AU to 50 AU from the Sun.

Space Mission Planning

Designing spacecraft trajectories and navigation systems. For example, calculating that the Voyager 1 spacecraft is over 150 AU from Earth as of 2023.

Etymology and History

The term "astronomical unit" was first used in the early 20th century to refer to the average distance between the Earth and the Sun. Historically, this distance was determined through observations of planetary transits, particularly the transit of Venus. The first accurate measurement was made by Giovanni Cassini in 1672 using parallax observations of Mars.

Over time, the definition of the AU evolved. In 1976, the International Astronomical Union defined it in terms of the Gaussian gravitational constant, making it dependent on the Sun's mass. However, in 2012, the IAU redefined the AU as exactly 149,597,870.7 kilometers, decoupling it from the Sun's mass and making it a fixed value. This change reflects the advancement of measurement science and the need for precise astronomical distance conversions.

Frequently Asked Questions

Why is the astronomical unit used in astronomy?

The astronomical unit provides a convenient scale for expressing distances within our solar system. Since planetary distances are enormous when expressed in kilometers or miles, using AU makes these numbers more manageable. For example, Jupiter is about 5.2 AU from the Sun, which is much easier to comprehend than 778 million kilometers.

How accurate is the AU definition?

The current definition of the astronomical unit is extremely accurate, fixed at exactly 149,597,870.7 kilometers. This definition was adopted in 2012 by the International Astronomical Union and is no longer dependent on measurements of the Earth-Sun distance or the Sun's mass. This fixed value ensures precise astronomical distance conversions.

How does AU compare to light-years and parsecs?

AU is used for solar system distances, while light-years and parsecs are used for much larger astronomical distances. Specifically, 1 light-year equals about 63,241 AU, and 1 parsec equals about 206,265 AU. Our astronomical unit converter tool can easily convert between these different scales of measurement.

How do I convert AU to other units?

Use our astronomical unit conversion calculators above, or multiply by the appropriate conversion factor. For example, to convert AU to kilometers, multiply by 149,597,870.7; to convert AU to miles, multiply by 92,955,807.3. For detailed instructions on converting AU to light-years, visit our AU to ly converter.

What are common uses for AU conversion?

AU conversion is essential in astronomy education, space mission planning, celestial mechanics calculations, and astronomical research. Whether calculating spacecraft trajectories or understanding planetary distances, our AU converter tool simplifies these complex measurements for scientists and enthusiasts alike.

How does AU conversion differ from other distance units?

AU is specifically designed for astronomical measurements within stellar systems, making it much more appropriate for solar system distances than terrestrial units like miles or kilometers. While meters are the SI base unit, AU provides a scale that's convenient for astronomical work, and our converter handles all these different systems.

Can I convert very large astronomical distances in AU?

Yes, our AU converter handles extremely large measurements with precision. For interstellar distances, you can convert AU to light-years or parsecs. For example, the nearest star system (Alpha Centauri) is about 270,000 AU away. Our smart rounding feature ensures readable results for all scales.

Is your astronomical unit conversion tool free to use?

Yes, our AU conversion calculator is completely free with no registration required. Simply enter your value, select your target unit, and get instant, accurate results. We believe precise astronomical measurement conversion should be accessible to everyone, from students to professional astronomers.