# Copyright (c) 2021, Rolfe Power

"""
    GRAVITATIONAL_CONSTANT

Universal constant of gravitation. [km^3 / (kg . s^2)]

Source: [NIST](https://physics.nist.gov/cgi-bin/cuu/Value?bg|search_for=universal_in!)
"""
const GRAVITATIONAL_CONSTANT = 6.6743e-20

"""
    ASTRONOMICAL_UNIT

Astronomical unit as defined by the IAU. [km]

Source: [IAU](https://www.iau.org/static/resolutions/IAU2012_English.pdf)
"""
const ASTRONOMICAL_UNIT = 149_597_870.700

"""
    EARTH_STANDARD_GRAVITY

Standard gravitational acceleration at surface of Earth. [km/s^2]

Source: [NIST](https://physics.nist.gov/cgi-bin/cuu/Value?gn|search_for=adopted_in!)
"""
const EARTH_STANDARD_GRAVITY = 9.80665e-03

"""
    PROTON_MASS

Mass of the proton. [kg]

Source: [NIST](https://physics.nist.gov/cgi-bin/cuu/Value?mp|search_for=atomnuc!)
"""
const PROTON_MASS = 1.67262192369e-27

"""
    NEUTRON_MASS

Mass of the neutron. [kg]

Source: [NIST](https://physics.nist.gov/cuu/Constants/Table/allascii.txt)
"""
const NEUTRON_MASS = 1.67492749804e-27

"""
    ELECTRON_MASS

Mass of the electron. [kg]

Source: [NIST](https://physics.nist.gov/cgi-bin/cuu/Value?mp|search_for=atomnuc!)
"""
const ELECTRON_MASS = 9.1093837015e-31

"""
    SPEED_OF_LIGHT

Speed of light in a vacuum. [km/s]

Source: [NIST](https://physics.nist.gov/cgi-bin/cuu/Value?c|search_for=adopted_in!)
"""
const SPEED_OF_LIGHT = 299792458e-3

"""
    BOLTZMANN_CONSTANT

Boltzmann constant. [J/K]
"""
const BOLTZMANN_CONSTANT = 1.380649e-23