# Semi-major axis: Quiz

Question 1: In ________, the semi-major axis is one of the most important orbital elements of an orbit, along with its orbital period.
AstrophysicsSunStarAstronomy

Question 2: For ________ objects, the semi-major axis is related to the period of the orbit by Kepler's third law (originally empirically derived),
Solar SystemSunPlutoEarth

Question 3: This form turns out to be a simplification of the general form for the ________, as determined by Newton:
Gravitational two-body problemEuler's three-body problemLaplace–Runge–Lenz vectorTwo-body problem

Question 4: In ________ semi-major axis a can be calculated from orbital state vectors:
Orbital mechanicsInterplanetary Transport NetworkGravity assistLagrangian point

Question 5: The semi-major axis' length a is related to the semi-minor axis b through the eccentricity e and the ________ , as follows:
Conic sectionParabolaEllipseHyperbola

Question 6: A ________ can be obtained as the limit of a sequence of ellipses where one focus is kept fixed as the other is allowed to move arbitrarily far away in one direction, keeping fixed.
ArchimedesParabolaConic sectionHyperbola

Question 7: where G is the ________, and M is the mass of the central body, and m is the mass of the orbiting body.
Gravitational constantPhysical constantForcePlanck units

Question 8: The major axis of an ________ is its longest diameter, a line that runs through the centre and both foci, its ends being at the widest points of the shape.
EllipseElliptic orbitOrbitConic section

Question 9: The semi-major axis of a ________ is, depending on the convention, plus or minus one half of the distance between the two branches; if this is a in the x-direction the equation is:
EllipseParabolaConic sectionHyperbola

Question 10: In ________ the orbital period T of a small body orbiting a central body in a circular or elliptical orbit is:
Interplanetary Transport NetworkLagrangian pointOrbital mechanicsGravity assist