# Physical Constants

Physical properties of celestial bodies and universal constants. All values use SI base units.

## Universal Constants

### C_LIGHT

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**Value**: `299792458.0` m/s

Speed of light in vacuum.

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### AU

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**Value**: `1.495978707e11` m

Astronomical Unit - mean distance of Earth from the Sun. TDB-compatible value.

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### P_SUN

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**Value**: `4.56e-6` N/m²

Solar radiation pressure at 1 AU.

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## Earth Constants

### Geometry

#### R_EARTH

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**Value**: `6378136.3` m

Earth's equatorial radius (GGM05 gravity model).

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#### WGS84_A

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**Value**: `6378137.0` m

Earth's semi-major axis as defined by WGS84 geodetic system.

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#### WGS84_F

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**Value**: `0.0033528106647474805` (dimensionless)

Earth's ellipsoidal flattening. WGS84 value: 1/298.257223563

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#### ECC_EARTH

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**Value**: `0.081819190842622` (dimensionless)

Earth's first eccentricity (WGS84 value).

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### Gravitational Properties

#### GM_EARTH

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**Value**: `3.986004415e14` m³/s²

Earth's gravitational parameter (μ = G × M).

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#### J2_EARTH

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**Value**: `0.0010826358191967` (dimensionless)

Earth's J2 zonal harmonic coefficient (GGM05s gravity model). Represents Earth's oblateness.

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#### OMEGA_EARTH

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**Value**: `7.292115146706979e-05` rad/s

Earth's axial rotation rate.

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## Celestial Body Gravitational Parameters

Gravitational parameters (μ = G × M) for major solar system bodies in m³/s².

### Sun

#### GM_SUN

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**Value**: `1.32712440041939e20` m³/s²

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#### R_SUN

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**Value**: `6.9634e8` m

Solar radius.

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### Moon

#### GM_MOON

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**Value**: `4.9028e12` m³/s²

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#### R_MOON

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**Value**: `1.738e6` m

Lunar radius.

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### Inner Planets

#### GM_MERCURY

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**Value**: `2.2031868551e13` m³/s²

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#### GM_VENUS

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**Value**: `3.257e14` m³/s²

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#### GM_MARS

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**Value**: `4.305e13` m³/s²

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### Outer Planets

#### GM_JUPITER

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**Value**: `1.268e17` m³/s²

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#### GM_SATURN

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**Value**: `3.794e16` m³/s²

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#### GM_URANUS

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**Value**: `5.794e15` m³/s²

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#### GM_NEPTUNE

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**Value**: `6.837e15` m³/s²

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### Dwarf Planets

#### GM_PLUTO

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**Value**: `9.77e11` m³/s²

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