About

In the vastness of space, standard integers fail. The distance light travels in a vacuum over one Julian year is a specific, colossal figure defined by the IAU. Converting this to kilometers produces numbers so large they exceed the display capacity of standard calculators, often resulting in errors or truncated precision. This tool is designed to handle these astronomical scales.

It is essential for visualizing distances to stars, nebulae, and galaxies. While astronomers often use Parsecs, the Light Year remains the most popular unit for public communication and science fiction. This converter manages the arithmetic of standard form (scientific notation) to provide accurate metric equivalents.

Formulas

The exact value of a Light Year is defined based on the Julian Year (365.25 days) and the speed of light (c).

c = 299,792,458 m/s

1 LY = 9,460,730,472,580.8 km

For input x Light Years, the calculation uses arbitrary precision logic:

d_km = x × 9.4607... × 10¹²

Reference Data

Object	Distance (Light Years)	Distance (Kilometers)
Oort Cloud (Inner Edge)	0.03 ly	2.8 × 10¹¹ km
Proxima Centauri	4.246 ly	4.01 × 10¹³ km
Sirius A	8.6 ly	8.14 × 10¹³ km
Galactic Center	26,000 ly	2.46 × 10¹⁷ km
Andromeda Galaxy	2,537,000 ly	2.40 × 10¹⁹ km
Observable Universe	93,000,000,000 ly	8.80 × 10²³ km

Frequently Asked Questions

This is scientific notation. "e+12" means "multiply by 10 to the power of 12". We use this because writing out 13+ zeros makes the number impossible to read quickly.

It is a measure of distance. It represents how far light travels in one year. It is approximately 9.46 trillion kilometers.

Even in Kilometers, the numbers are huge. Using meters would add three more zeros, making the notation even more unwieldy without adding significant precision for general use.

Yes. The tool supports inputs up to the safe integer limit of JavaScript, which far exceeds the diameter of the observable universe (approx 93 billion light years).