# Astronomical Units to Fathoms (au to ftm)

Source: https://www.unitconvertercalculator.com/length/astronomical-units-to-fathoms/

**1 au = 81801110400.262 ftm**

One astronomical unit equals approximately 8.181 x 1010 fathoms, or about 81.8 billion fathoms. This conversion connects the solar system distance unit with the maritime depth unit (6 feet / 1.8288 m). No oceanographer has ever measured interplanetary distances, and no astronomer has measured ocean depths in AU.

## Formula

Convert Astronomical Units to Fathoms

## Conversion Table

| Astronomical Units (au) | Fathoms (ftm) |
|---|---|
| 1.0E-10 au | 8.1801110400262 ftm |
| 1.0E-9 au | 81.801110400262 ftm |
| 1.0E-8 au | 818.01110400262 ftm |
| 1.0E-7 au | 8180.1110400262 ftm |
| 1.0E-6 au | 81801.110400262 ftm |
| 1.0E-5 au | 818011.10400262 ftm |
| 0.0001 au | 8180111.0400262 ftm |
| 0.001 au | 81801110.400262 ftm |
| 0.01 au | 818011104.00262 ftm |
| 0.1 au | 8180111040.0262 ftm |
| 1 au | 81801110400.262 ftm |

## Units

### Astronomical Unit (au)

Exactly 149,597,870,700 meters by IAU 2012 definition. Roughly the average distance from the Earth to the Sun. Used for distances within our solar system.

### Fathom (ftm)

Exactly 6 feet (1.8288 m). Traditionally used to measure water depth in nautical contexts. Originally based on the span of outstretched arms.

## Background

The deepest ocean point (Challenger Deep at about 6,000 fathoms) is only 0.0000000733 AU below sea level. Conversely, the Earth-Sun distance would be about 81.8 billion fathoms of ocean depth if such a thing existed. These numbers illustrate the vast difference between oceanographic and astronomical scales.

## Good to Know

Shakespeare's 'full fathom five' (30 feet) and the 93-million-mile Earth-Sun distance represent perhaps the most extreme contrast between literary and scientific measurement. Both are valid ways of understanding distance, just at incompatible scales.

## FAQ

### How many fathoms are in 1 AU?

One AU contains approximately 8.181 x 1010 fathoms (about 81.8 billion fathoms). Since 1 AU = 149,597,870,700 meters and 1 fathom = 1.8288 meters, divide the former by the latter.

### How deep is the Challenger Deep in AU?

The Challenger Deep at about 10,994 meters (6,011 fathoms) is approximately 7.35 x 10-8 AU, or about 74 billionths of an AU. The entire ocean is a tiny scratch on the astronomical scale.

### Does anyone convert between AU and fathoms?

No. These units belong to completely separate fields: astronomy and maritime navigation. The conversion exists only for mathematical completeness in unit conversion tools.

## Non-Frequently Asked Questions

### Could you anchor a ship to the Sun?

Anchor chain is measured in fathoms. The Earth-Sun distance is about 81.8 billion fathoms. The longest anchor chain ever made is a few hundred fathoms. You would be short by about 81,799,999,700 fathoms. And it would melt.

### How deep would a space ocean need to be to hold 1 AU?

If space were an ocean 1 AU deep, that would be about 81.8 billion fathoms. The real ocean's deepest point is about 6,011 fathoms. A space ocean would be 13.6 million times deeper than the Mariana Trench. Bring a longer anchor chain.

### Is space fathomable?

Literally, no. To fathom means to measure depth with a plumb line. Space has no bottom. Even metaphorically, 81.8 billion fathoms of distance is beyond fathoming. Space is, quite literally, unfathomable.

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## See Also

- [Fathoms to Astronomical Units](https://www.unitconvertercalculator.com/length/fathoms-to-astronomical-units/)