#####
##### UniversalConstants
#####

# These constants are planet-independent.

export gas_constant,
       light_speed,
       h_Planck,
       k_Boltzmann,
       Stefan,
       astro_unit,
       avogad

"""
    gas_constant

Universal gas constant (J/mol/K)
"""
gas_constant() =     8.3144598

"""
    light_speed

Speed of light in vacuum (m/s)
"""
light_speed() =      2.99792458e8

"""
    h_Planck

Planck constant (m^2 kg/s)
"""
h_Planck() =         6.626e-34

"""
    k_Boltzmann

Boltzmann constant (m^2 kg/s^2/K)
"""
k_Boltzmann() =      1.381e-23

"""
    Stefan

Stefan-Boltzmann constant (W/m^2/K^4)
"""
Stefan() =           5.670e-8

"""
    astro_unit

Astronomical unit (m)
"""
astro_unit() =       1.4959787e11

"""
    avogad(::Type{FT})

Avogadro's number [molec/mol]
"""
avogad() = 6.02214076e23
