The point of closest approach is called the periapsis or pericentre and the point of farthest excursion is called the apoapsis (Greek από, "from", which becomes απ before a vowel, and αφ before rough breathing), apocentre or apapsis (the latter term, although etymologically more correct, is much less used). A straight line drawn through the periapsis and apoapsis is the "line of apsides". This is the major axis of the ellipse, the line through the longest part of the ellipse.