Astronomical Units to Yards (au to yd)

1 astronomical unit equals 163,602,220,801 yards (rounded).

1 astronomical unit = 163,602,220,801 yards

How to convert astronomical units to yards

To convert astronomical units to yards, multiply the number of astronomical units by 163,602,220,801. The factor is rounded to 10 significant digits. To go the other way, multiply yards by 6.112386465×10⁻¹² (rounded).

yards = astronomical units × 163,602,220,801

Example: 10 astronomical units = 1,636,022,208,005 yards.

About these units

Astronomical Unit (au)

AstronomicalCurrent unit

Exactly 149,597,870,700 meters, roughly the average distance from the Earth to the Sun. Used for distances within the solar system.

Astronomers began calling it the astronomical unit in the mid-nineteenth century, with the name first recorded in 1848, though the quantity itself had been chased since antiquity. Aristarchus put the Sun 18 to 20 times farther away than the Moon, when the true ratio is about 389. Cassini and Richer used the parallax of Mars in 1672, transits of Venus served for generations, and radar echoes from Venus and Mars in the early 1960s finally gave direct distances.

For most of the twentieth century the unit was tied to the Gaussian gravitational constant, which meant its value had to be remeasured as observations improved. In 2012 the IAU removed that dependence by fixing it at exactly 149,597,870,700 meters and recommending the symbol au. The figure used here is that exact value. It is close to the mean Earth-Sun separation, which varies from about 0.983 au at perihelion to about 1.017 au at aphelion. Light needs roughly 499 seconds to cross one au, and Neptune orbits at about 30 au.

1 astronomical unit = 149,597,870,700 meters (exactly).

Sources: Wikipedia: Astronomical unit; NIST SP 811 Appendix B.8: factors for units outside the SI; Wikipedia: Light-second

Yard (yd)

US & ImperialCurrent unit

3 feet or 36 inches, exactly 0.9144 meters. Used for sports fields, fabric and short distances in the US and UK.

Yard descends from the Old English gerd or gyrd, meaning a branch, stave or measuring rod. It first appears in the late seventh-century laws of Ine of Wessex, though there it names a tax unit, the yardland. Around 959 to 963 King Edgar ordered that the measure held at Winchester be used throughout his realm, the earliest record of a prototype. A story that Henry I fixed the yard as the distance from his nose to his thumb is later folklore, and the true origin, whether pace, cubit or waist, remains speculative.

Britain defined the Imperial Standard Yard in 1824 as the distance between two marks on a brass rod at 62 degrees Fahrenheit. A fire in 1834 damaged the standard, a replacement was made in 1845, and the Weights and Measures Act 1855 recognized it. The 1959 international agreement then fixed the yard at exactly 0.9144 meter. Today it measures American and Canadian football fields, association football pitches and cricket pitches, appears on UK road signs for short distances, and is still used to sell fabric in the US and UK.

1 yard = 0.9144 meters (exactly).

Sources: Wikipedia: Yard; Wikipedia: Inch; NIST Guide to the SI, Appendix B.8: conversion factors

Related conversions

See all length units.