JTS.orthodromicDistance incorrectly calculate the equatorial radius of the earth

Question

JTS.orthodromicDistance(new Coordinate(0,0), new Coordinate(180,0), DefaultGeographicCRS.WGS84) * 2 is equal to 40075016 but must be equal to 6378000.

Answer 1

You get what you asked for. Your formula calculates the circumference, which is 2*pi*radius.

The radius is circumference / (2*pi), indeed about 6378000.