sed neque in Arctoo sedem tibi legeris orbe
nec polus aversi calidus qua vergitur Austri,
unde tuam videas obliquo sidere Romam.
aetheris inmensi partem si presseris unam,
sentiet axis onus. librati pondera caeli
orbe tene medio; pars aetheris illa sereni
tota vacet nullaeque obstent a Caesare nubes.
But you will not have chosen a seat for yourself in northern climes,
nor where the warm pole of the opposed south lies,
whence you would see your Rome from sidelong star.
If you will have pressed [only] one part of the huge heaven,
the whole sky will feel the burden. Hold the weights of balanced
heaven in the middle of the world; let that whole part of the calm
air be empty and let no clouds stand in the way of Caesar.
Notes:
unde…videas: I am taking this as a relative clause of result.
librati: Would ‘suspended’ be better here, following off of the possibility of Nero pressing down one part of the sky and thus ‘burdening’ the rest of the sky (or causing it to sink or to ‘not hang’ properly [cf. LS s.v. libro II.B])? But then again, ‘balanced’ conveys the opposite of the possibility of throwing out of kilter in the previous sentence. Perhaps there’s an ambiguity in the Latin that doesn’t come across well in English.
sereni: The sky is presumably calm now, but the word may have a proleptic coloring as well (in the rhetorical, not grammatical, sense): if Nero avoids planting himself in the sky, it will remain calm.
obstent a Caesare: obstare is usually constructed with the dative. Should this be understood as an ablative of separation, i.e., may clouds not hinder/keep back Rome from [the eyes of] Nero?