What is an astronomical unit (AU)?

An astronomical unit is a length defined as exactly 149,597,870,700 metres, corresponding to the average distance from Earth to the Sun, used mainly within Solar System measurements.

What does a light year (ly) represent?

A light year is the distance light travels in vacuum in one Julian year (365.25 days), approximately 9.4607 × 10^15 metres, often used for interstellar distances.

Why convert from AU to light years?

Converting from astronomical units to light years helps translate Solar System scale distances into broader cosmic scales for astronomy and educational outreach.

How to Convert from Astronomical unit [AU, UA] to Light year [ly]?

Learn how to convert distances measured in astronomical units (AU) to light years (ly) with this easy-to-use unit converter. Understand when and why to use each unit for astronomical calculations.

Astronomical unit [AU, UA]

Light year [ly]

Please check your input. It must be a valid numeric value.

Astronomical unit [AU, UA] to Light year [ly] Conversion Table

Astronomical unit [AU, UA]	Light year [ly]

Custom Unit Conversion Table Generator – Instant Printable Conversion Tables

Start Value

Enter the starting number (positive decimal or integer ≥ 0). Example: 0.1, 1, 5.

End Value

Enter the ending number (positive decimal or integer > Start Value). Example: 10, 50, 100.

Interval

Enter the step size (positive decimal > 0 and < End Value – Start Value). Example: 1.0, 2.5.

Astronomical unit [AU, UA] to Light year [ly] Conversion Table
Astronomical unit [AU, UA]	Light year [ly]

Explore More Length Units Converter

What Is This Tool?

This converter transforms length measurements given in astronomical units (AU, UA) into light years (ly). It provides a straightforward way to switch between scales used within the Solar System and those used for interstellar distances.

How to Use This Tool?

Enter the length value in astronomical units (AU or UA).
Select astronomical unit as the input unit and light year as the output unit.
Click convert to view the equivalent distance in light years.

Key Features

Converts astronomical units to light years using exact defined rates.
Browser-based tool requiring no installation or downloads.
Supports usage in astronomy, astrophysics, and space mission planning.

Examples

5 astronomical units equals 0.0000790625 light years.
100 astronomical units equals 0.00158125 light years.

Common Use Cases

Expressing planetary orbital radii and semi-major axes within the Solar System.
Describing spacecraft trajectories and mission plans.
Translating solar system distances into the cosmic scales used for interstellar measurements.

Tips & Best Practices

Use astronomical units for distances within the Solar System for convenience.
Switch to light years when dealing with distances between stars or galaxies.
Confirm unit selections before conversion to ensure accurate results.

Limitations

Astronomical units are practical only for Solar System scales and not suitable for interstellar distances.
Light years are better for cosmic scales, making AU impractical beyond the solar neighborhood.
Differences in scale and context limit the precision when converting between these units.

Frequently Asked Questions

What is an astronomical unit (AU)?: An astronomical unit is a length defined as exactly 149,597,870,700 metres, corresponding to the average distance from Earth to the Sun, used mainly within Solar System measurements.
What does a light year (ly) represent?: A light year is the distance light travels in vacuum in one Julian year (365.25 days), approximately 9.4607 × 10^15 metres, often used for interstellar distances.
Why convert from AU to light years?: Converting from astronomical units to light years helps translate Solar System scale distances into broader cosmic scales for astronomy and educational outreach.

Key Terminology

Astronomical unit (AU, UA): A unit of length defined as exactly 149,597,870,700 metres, representing the average Earth-Sun distance, used to measure distances within the Solar System.
Light year (ly): A unit of length equal to the distance light travels in one Julian year, about 9.4607 × 10^15 metres, used mainly for interstellar distances.

Quick Knowledge Check

What does 1 astronomical unit approximately equal in light years?

0.0015 light years

0.0000158125 light years

1.5 light years

What unit is more suitable for expressing distances within the Solar System?

Light year

Astronomical unit

Kilometre

Which unit is commonly used to express distances to stars?

Astronomical unit

Light year

Metre

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