Hasta que + subjuntivo vs. indicativo

Question

Hola,I took the full-in-the-blanks quiz "Asando Castañas" today and one of the blanks, where I should choose between El Subjunctivo Presente and El Indicativo Presente, was the following:muchas personas se suman a ella con tal de pasar un buen rato,hasta que ______ (llega/llegue) el amanecer.Apparently the correct answer was El Indicativo (llega not llegue), but I don't understand why. Isn't sunrise a future event that is yet to happen and therefore the sentence requires El Subjunctivo?Thanks as always!Deborah

Accepted Answer

Hola Deborah
Interesting one!
It requires the indicative because if we re-read the whole sentence:
"y muchas personas se unen a ella hasta que llega el amanecer."
we can see that we are talking about a "habitual action": lots of people "do" join in until dawn arrives. The bit "until dawn arrives" is also part of that habitual action, so every time they join in it is until dawn arrives (every time). We have a sentence in the lesson where you can see the similarity, interpreting it as an habitual action:
A veces espero a mi hija despierta hasta que llega a casa.
Sometimes I wait up for my daughter until she gets home.
I'll give you a couple more sentences using the indicative so you can see it more clearly:

Nunca salgo de casa hasta que compruebo que las ventanas están cerradas.
I never leave the house until I check all the windows are shut.
Estuvimos viendo la peli hasta que llegaron sus padres.
We watched the film until his parents arrived.
A veces leo en la cama hasta que me quedo dormida.
Sometimes I read in bed until I fall asleep.

I understand "hasta que" clauses can present an extra difficulty when choosing indicative or subjunctive because when we see "hasta que" we take it as a future action. We will consider to add an extra hint to that bit of test in the gap-fill to clarify a bit more what is expected for that gap. I hope it helps.
Saludos
Inma