Inch to Astronomical Unit Converter

An inch is a unit of length in the imperial and US customary systems equal to 1/12 of a foot or approximately 2.54 centimeters. It is used for precise measurements of smaller objects.

The inch has ancient origins, possibly derived from the width of a man's thumb. The word comes from the Latin 'uncia' meaning 'twelfth part'. It was standardized in England and later defined internationally as exactly 25.4 millimeters in 1959.

Inches are widely used in the United States for measuring screen sizes, pipe diameters, lumber dimensions, and precision measurements in manufacturing. They're standard for tools, fasteners, and many consumer products in countries using imperial measurements.

An astronomical unit (AU) is a unit of length approximately equal to the average distance from Earth to the Sun, defined as exactly 149,597,870.7 kilometers or about 93 million miles.

The astronomical unit was originally defined as the semi-major axis of Earth's orbit around the Sun. It was first estimated by Giovanni Cassini in 1672 and has been refined over centuries. In 2012, the International Astronomical Union redefined it as an exact value rather than a measured quantity.

Astronomical units are primarily used for measuring distances within the solar system, including distances between planets, asteroids, and comets. They're standard in planetary science, space mission planning, and solar system astronomy.