Convert Earth's Equatorial Radius to Astronomical Unit
Convert earth's equatorial radii to astronomical units instantly. 1 earth's equatorial radius = 4.263521e-5 astronomical unit — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Astronomical Unit to Earth's Equatorial Radius converter for the reverse conversion.
Units explained
Earth's Equatorial Radius
Earth's equatorial radius is the distance from the planet's center to its surface at the equator, defined as exactly 6,378,137 meters by the WGS84 geodetic reference system.
The WGS84 (World Geodetic System 1984) defines Earth's reference ellipsoid for use in GPS and global cartography. The 6,378,137 m equatorial value was determined through satellite and ground geodetic measurements consolidated in 1984.
WGS84's equatorial radius is the standard reference for GPS, satellite imagery, geographic information systems, and aviation navigation. It defines the 'a' parameter of Earth's reference ellipsoid in coordinate transformations.
WGS84 reference ellipsoid adopted in 1984 by the US Department of Defense; subsequently adopted globally for GPS and civilian geodesy.
Astronomical Unit
The astronomical unit (AU) is a unit of length equal to exactly 149,597,870,700 meters, approximately the average distance from Earth to the Sun. It is the fundamental unit for distance within the solar system.
The AU was originally defined as the semi-major axis of Earth's orbit. In 2012, IAU Resolution B2 redefined the AU as exactly 149,597,870,700 meters, severing its dependence on the actual fluctuating Earth–Sun distance.
AUs are used to express distances within the solar system (Mars: 1.5 AU, Pluto: ~40 AU at perihelion), exoplanet orbital radii, and other planetary-scale distances. Standard in planetary science and astronomy.
Original definition tied to Earth's orbit (Newton, 17th century); fixed at exactly 149,597,870,700 m by IAU Resolution B2 in 2012.
Earth's Equatorial Radius to Astronomical Unit conversion formula
The relationship between earth's equatorial radii and astronomical units:
To convert earth's equatorial radii to astronomical units, multiply the value in earth's equatorial radii by 4.263521e-5. To reverse, multiply astronomical units by 23454.7910620296.
How to use this converter
Type a value into the calculator. The result in astronomical units updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the Astronomical Unit to Earth's Equatorial Radius converter for the reverse direction.
Step-by-step: convert earth's equatorial radii to astronomical units
- Write down the value in earth's equatorial radii (R⊕,eq).
- Multiply that value by the factor 4.263521e-5.
- The product is the equivalent value in astronomical units (AU).
- To reverse, multiply the astronomical unit value by 23454.7910620296.
Worked examples
Example 1 — Convert 1 R⊕,eq to AU:
1 × 4.263521e-5 = 4.263521e-5 AU
Example 2 — Convert 100 R⊕,eq to AU:
100 × 4.263521e-5 = 0.0042635212 AU
Earth's Equatorial Radius to Astronomical Unit conversion table
Standard reference values for converting earth's equatorial radii to astronomical units:
| Earth's Equatorial Radius [R⊕,eq] | Astronomical Unit [AU] |
|---|---|
| 0.01 | 4.263521e-7 |
| 0.1 | 4.263521e-6 |
| 1 | 4.263521e-5 |
| 2 | 8.527042e-5 |
| 3 | 0.0001279056 |
| 4 | 0.0001705408 |
| 5 | 0.0002131761 |
| 10 | 0.0004263521 |
| 20 | 0.0008527042 |
| 30 | 0.0012790564 |
| 40 | 0.0017054085 |
| 50 | 0.0021317606 |
| 100 | 0.0042635212 |
| 500 | 0.0213176062 |
| 1000 | 0.0426352125 |
Frequently asked questions
How many astronomical units is 1 earth's equatorial radius?
How do I convert earth's equatorial radii to astronomical units?
How do I convert astronomical units back to earth's equatorial radii?
How many astronomical units is 100 earth's equatorial radii?
Popular length unit conversions
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Metric / SI (4 units)
Imperial / US Customary (4 units)
Astronomical (8 units)
Sources & references
Conversion factor (1 R⊕,eq = 4.263521e-5 AU) verified against the following authoritative sources:
- BIPM — The International System of Units (SI Brochure 9th ed.)
Official BIPM publication defining the seven SI base units (including the meter) and the rules for their use. The global authority on units of measurement.
- NIST — Guide to the SI
US National Institute of Standards and Technology reference covering the SI base and derived units with definitions and usage rules for US technical practice.
- NIST Special Publication 811 — Guide for the Use of the International System of Units
Detailed NIST guide covering exact conversion factors between SI and US customary units along with formatting and rounding conventions.
- NIST — Refinement of values for the yard and pound (Federal Register 1959)
The treaty (signed by US
- International Astronomical Union — System of Astronomical Constants
The IAU defines astronomical units including the AU (149597870700 m exactly) light-year and parsec used in astronomy and astrophysics.