If an object with comparable mass to that of the Earth were to fall towards it, then the corresponding acceleration of the Earth would be observable.
(an object with comparable mass to that of the Earth; were; to fall towards it) (an object with comparable mass to that of the Earth; to fall; towards it)
an object with comparable mass to that of the Earth an object with comparable mass to that of the Earth
were to fall
to fall towards it
towards it