Assertion: ellipse's axis | /r/ObjectUse | used in astronomy
Facets:
value: sometimes
type: TEMPORAL
Source sentences:
text: The semi-major axis is sometimes used in astronomy as the primary-to-secondary distance when the mass ratio of the primary to the secondary is significantly large ( M ≫ m {\displaystyle M\gg m} ); thus, the orbital parameters of the planets are given in heliocentric terms.