Gigameter is 1000000000 meter units.
Gigameters to Astronomical units Converter — Gm to AU
Convert Gigameter (Gm) to Astronomical unit (AU) using the exact conversion factor (1 gigameter = 0.0066845871 astronomical unit). See the formula, worked examples, conversion table, history, and common uses.
Gigameters to Astronomical units converter
Converter
Length Converter
Convert SI, imperial, US customary, astronomical, scientific, and historical length units.
Context values
Some unit families need one extra value for a physically accurate result.
An astronomical unit is the mean Earth-Sun distance.
Result = input x 1e+9 / 1.49597871e+11.
Length uses the meter as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Gigameters to Astronomical units
Gigameter and Astronomical unit both measure length. Specifically: Gigameter is 1000000000 meter units, and an astronomical unit is the mean Earth-Sun distance.
Formula
astronomical units = gigameters × 0.00668458712227
This factor comes from each unit's defined relationship to the category's base unit: 1 gigameter equals 1000000000 base units, and 1 astronomical unit equals 149597870700 base units, so dividing one by the other gives the direct gigameter-to-astronomical unit factor of 0.00668458712227.
Simple example
1 Gm × 0.006684587122 = 0.0066845871 AU
1 gigameter = 0.0066845871 astronomical units.
Real-world example
10 Gm × 0.006684587122 = 0.0668458712 AU
10 gigameters = 0.0668458712 astronomical units.
Conversion table
| Gigameter (Gm) | Astronomical unit (AU) |
|---|---|
| 1 Gm | 0.0066845871 AU |
| 5 Gm | 0.0334229356 AU |
| 10 Gm | 0.0668458712 AU |
| 21.0975 Gm | 0.1410280768 AU |
| 42.195 Gm | 0.2820561536 AU |
| 100 Gm | 0.6684587122 AU |
Reverse conversion: Astronomical unit to Gigameter
0.0066845871 AU × 149.5978707 = 0.9999999967 Gm
0.0066845871 astronomical units = 0.9999999967 gigameters.
gigameters = astronomical units × 149.5978707
For a page dedicated to this direction, see Astronomical unit to Gigameter.
Understanding the Gigameter (Gm)
Gigameter is 1000000000 meter units.
Understanding the Astronomical unit
Astronomical unit (AU) measures distance. The astronomical unit is defined as exactly 149,597,870,700 meters, close to the average Earth-Sun distance. It is classified as a Non-SI unit accepted for use with SI (astronomical).
Where it's used: Used internationally in astronomy for solar-system-scale distances.
Uses of the Astronomical unit today
- Measuring distances within the solar system (planetary orbits)
- Astronomical calculations and spacecraft navigation
- Popular science communication about the solar system
History of the Astronomical unit
The astronomical unit originated from 17th-19th century attempts to measure the Earth-Sun distance, refined over time using transits of Venus and later radar and spacecraft ranging.
In 2012, the International Astronomical Union fixed the AU at exactly 149,597,870,700 meters, replacing its earlier definition (tied to gravitational calculations) with a simple fixed distance, independent of the slightly-variable actual Earth-Sun distance.
Historical origin. Astronomical unit was not the invention of a single named person; it developed through the process described above.
Astronomical unit — sources
- IAU Resolution B2 (2012) — Fixes the astronomical unit at exactly 149,597,870,700 meters.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many astronomical units are in 1 gigameter?
1 gigameter equals 0.0066845871 astronomical units, using the exact defined conversion factor rather than an estimate.
How do I convert gigameter to astronomical unit?
Multiply the gigameter value by 0.006684587122. The converter above does this instantly to whatever precision you set.
How do I convert astronomical unit back to gigameter?
Use the reverse factor: 1 astronomical unit equals 149.5978707 gigameters. You can also use the swap control in the converter above to flip the direction instantly.
What is a gigameter?
Gigameter (Gm) is a unit of length.
What is a astronomical unit?
Astronomical unit (AU) measures distance. The astronomical unit is defined as exactly 149,597,870,700 meters, close to the average Earth-Sun distance. It is classified as a Non-SI unit accepted for use with SI (astronomical).
Is the gigameter to astronomical unit conversion exact?
Yes. The astronomical unit is defined as exactly 149,597,870,700 meters, close to the average Earth-Sun distance. That fixed definition is what the converter above uses, so any rounding you see is a display choice, not a limitation of the math.