The Constants of Astrogation

1. The Speed of Light:

2. The Astronomical Unit: Originally astronomers defined the astronomical unit as the length of the semi-major axis of Earth's orbit. In 1976 the International Astronomical Union redefined it as the radius of a perfectly circular, unperturbed orbit on which a particle of negligible mass in free fall would need precisely 365.2568983 siderial days to go around it once. It has its most precise value as 149,597,870.691 meters.

3. The Lightyear:

4. One Gee:

5. The Sun's Gravitational Constant: (for other stars, multiply by the star's mass expressed as a multiple of Sol's mass)

6. Earth's Gravitational Constant: (for other planets, multiply by the planet's mass expressed as a multiple of Earth's mass)

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