Breakdown of Não consigo ver nada a não ser que o telescópio esteja aqui.
não
not / no
aqui
here
estar
to be (temporary / location)
ver
to see
Questions & Answers about Não consigo ver nada a não ser que o telescópio esteja aqui.
Why is the verb esteja in the subjunctive mood here?
The phrase a não ser que (unless) expresses a condition or an exception to the main clause. In Portuguese, this type of subordinating conjunction always triggers the subjunctive mood because it sets up a hypothetical situation. Therefore, the indicative está becomes the present subjunctive esteja.
Could I use a menos que instead of a não ser que in this sentence?
Yes, they are completely interchangeable. Both mean 'unless' and both require the following verb to be in the subjunctive. You could say ...a menos que o telescópio esteja aqui without changing the meaning at all.
Since we are using the subjunctive, why do we use esteja (from estar) instead of seja (from ser)?
The rules for choosing between ser and estar still apply exactly the same way in the subjunctive mood. Because we are talking about the physical, temporary location of the telescope (aqui), we must use the verb estar.
Why does the sentence use both não and nada?