############################################################
# Program is part of MintPy                                #
# Copyright (c) 2013, Zhang Yunjun, Heresh Fattahi         #
# Author: Zhang Yunjun, Feb 2022                           #
############################################################
# Recommend usage:
#   from mintpy.constants import SPEED_OF_LIGHT


SPEED_OF_LIGHT = 299792458  # meters per second

# Earth radius
# equatorial radius: a = 6378.1370e3
# polar      radius: b = 6356.7523e3
# arithmetic mean radius: R_1 = (2 * a + b) / 3 = 6371.0088e3
#   defined by IUGG and used in geophysics
EARTH_RADIUS = 6371.0088e3   # the arithmetic mean radius in meters