Thank you, The9! That answers a lot of questions! So the first hour is from sunrise, the sixth hour is at midday, and the twelfth hour is the last before sunset.
It's interesting that the article doesn't mention Ante Meridiem and Post Meridiem, the one little bit of Latin that everybody knows. Instead,
To indicate that it is a day or night hour Romans used expressions such as for example prima diei hora, prima noctis hora, hora prima noctis.
From this very interesting page:
The Roman civil & religious day began at midnight" (...)
[Some scholars say] the hours were counted from dusk to dawn, hence that the 6th hour of the night represented [midnight and the 6th of the day, midday]. (see the "siesta" explanation above).
The page says that, but I think it's a contradiction? As dusk (sunset) is not always at the same hour.
Noon, in English, is from the Latin "Nona hora", for the 9th hour, and the Spanish siesta (that was borrowed by the other Romance language in siesta, and sieste) means 6th hour, sexta hora (noon I guess, because a nap at midnight would be normal).
So "noon", the 9th hour, wasn't 12 p.m (lunch time).
A bit confusing, between 6th hour and 9th hour, being both 12 p.m (lunch time), but it seems that scholars who said that it was not counted from midnight, but rather from the sunset (dusk) were right in this case. It seems more logical. Why would the 9th hour equivalent to the 12th hour from midnight in other cases?
Dusk can be +/- 3 hours easily.
They had sometimes their "noon" at 2 p.m sometimes at 11 p.m. Not always at the same of our hours.
And no sun dial working at midnight! So how they could start their day timing? I guess they could use clepsidra to monitor time when the sun dial was off. But it wasn't really needed. It's better to consider the beginning of the Roman day was the sunset hour: easy to notice.
I think the confusion here comes from the "est".
If it's a time, a hour of the day, I expected rather "The first hour before noon".
The "est" seems a description here, as when I explain arithmetic. The first hour is before the 2nd hours, etc...
Is the confusion only for me? Were Romans saying "est" to count the hours?
Actually, it is correct. If you read the Wikipedia page that The9 referenced above, you will understand. Unfortunately I wrote, "It is one a.m." and reported it as an acceptable alternate, but now I see it isn't. My apologies to the course contributors. The translation of my sentence would be, "Prima noctis hora est."
So let's say the first hour is 7 a.m. our time, that means 11 a.m. our time is the fifth hour. Would the Romans have said "It is the first hour before noon" to mean "it is the fifth hour?" Or would they always say "It is the fifth hour?" If they did say it the first way also, how would you say that in Latin? Wouldn't it also be "Prima hora ante meridiem est" or would it be something different? Anyone know?
Yes. Prepositions need objects, and that's the prepositional phrase: ante meridiem (before midday).