Irish: an dá geábh gar úd

[se16teddy]

Hello! I wonder if someone could help me with a bit of Irish please? It is from Hallowe’en‘s Nuacht Mhall. 31 Deireadh Fómhair 2020 (Maigh Eo) - Nuacht Mhall
The whole sentence is:
Tiocfaidh Apophis an-ghar don domhan i 2029 agus arís i 2036, agus cé nach bhfuil baol ar bith d’imbhualadh sna blianta sin, braitheann céard a tharlóidh i 2068 go h-an íogair ar an dá geábh gar úd; agus ar an tionchar beag a mhothaíonn Apophis ó sholas na gréinne an t-am uilig, an “éifeacht Yarkovsky”, atá thar a bheith deacair a ríomh go cruinn.
I am stuck on this bit in the middle, which I guess will work as an independent sentence:
braitheann céard a tharlóidh i 2068 go h-an íogair ar an dá geábh gar úd
I suppose it means
What is going to happen in 2068 depends (breitheann) in a very sensitive way on (ar) that distant (úd) close visit (geábh)
But this translation ignores dá! What is the role of dá?

 

[Scaith]

An dá = the two
With overall meaning, "what happens in 2068 depends very sensitively on those two very close passes to come"

 

[Scaith]

An dá = the two
With overall meaning, "what happens in 2068 depends very sensitively on those two very close passes to come"

*what WILL happen

 

[se16teddy]

Thank you, Scaith. I was confused because I have not seen dhá unlenited before. Singular-looking an didn't help either! but I suppose it makes sense because nouns are in the singular after numerals.