In the magazine Astronomy Now I find the following sentence as caption to an image:
NGC 5256 is a pair of galaxies in its final stage of merging
My reading is that ‘its’ is incorrect and that it should be ‘their’. My reasons are:
- the possessive pronoun must surely qualify the plural noun ‘galaxies’ rather that the singular noun ‘pair’;
- the participle ‘merging’ must similarly qualify ‘galaxies’ and not ‘pair’.
But is that right?