Circular Velocity Calculator Computes the circular orbital velocity of an object. Velocity Calculator Computes the orbital velocity of an object. Escape Velocity Calculator Computes the escape velocity of an object. Period Calculator Computes the orbital period of an object. Semi-Major Axis Calculator Computes the semi-major of an object from its period. Visual Magnitude Calculator Computes the visual magnitude of a star from its absolute magnitude and distance. Hill Sphere Calculator Computes the Hill Sphere of an object Sail Calculator Computes the maximum velocity possible from acceleration caused by light pressure Interior Reach Formula Computes the distance interior to a planet where the planet's gravity will make the region unstable for other planets. See this paper by Barrie W. Jones, et.al. for an explanation and use their table to obtain a value for n. Exterior Reach Formula Computes the distance Exterior to a planet where the planet's gravity will make the region unstable for other planets. Stellar Encounter Calculator Computes the number of stars expected to pass within a given distance of the Sun over a specified period of time. Kozai eccentricity calculator Computes the maximum eccentricity obtained by a planet due to the Kozai mechanism. Kozai period calculator Computes the period of time for the Kozai mechanism to cause a planet's orbit to go from maximum to minimum eccentricity and back to maximum eccentricity. Poynting-Robertson calculator Computes force on an object due to the Poynting-Robertson effect, in which sunlight causes objects to spiral in towards the sun. Effective Radius Calculator Computes the effective radius of an object due to its gravity given the velocity at infinity of an approaching object. Lagrange Point Finder Computes the distance to the the 5 Lagrange points, and the velocity of the point. Orbital Elements Cartesian Coordinates converter Converts between orbital elements and Cartesian coordinates and state vectors Cramer's Rule Solve a 3 x 3 matrix using Cramer's Rule Equatorial to Ecliptic Converts from equatorial to ecliptic coordinates