Before the Motu Propio "Sacram Communionem. On Laws of Fasting and the Evening Mass" of Pope Pius XII in 1957, the rule of c. 821 § 1 CIC/1917 applied in the Catholic Church as a ruling on the times for celebrating mass. The codex is from 1917, but I suspect the rule is older (maybe Council of Trent?).

c. 821 § 1 CIC/1917: Missae celebrandae initium ne fiat citius quam una hora ante auroram vel serius quam una hora post meridiem.

The beginning of the celebrated mass shall not be before one hour before aurora and later than one hour after midday. [my translation]

What does aurora means in this context? Is it sunrise, the beginning of the red sky at morning or something else? Was there a definition or practical formula in the canonical literature? As this question was practically relevant for every priest there should be at least some rule of thumb.

This question is different from Can Mass be celebrated at any hour of the day?. The scope of that question is broader and in Geremia's Answer the word aurora is just translated with sunrise without explanation. I want the details here.

  • Dawn, sunrise or twilight? It is a question of nuance. Aurora means "dawn" in English, but can be interpreted as sunrise.
    – Ken Graham
    Commented Mar 1, 2019 at 22:29
  • @KenGraham And this nuance is the question here. I cannot imagine there was no canonist thinking about this.
    – K-HB
    Commented Mar 1, 2019 at 22:37
  • Edward Peters translation of the 1917 code, published 2001, translates aurora as first light, but although this is well before sunrise I'm not sure how it was defined. It cannot have been observation as the mass can start an hour before first light, at which time it would not have been observed. The Irish Catholic Almanac for 1920 has sunrise, sunset and similar info but no first light. One might expect time of earliest mass to be published for every day and all major cities, but it seems not. Perhaps priests erred on side of caution and stayed in bed, but there must have been some rule.
    – davidlol
    Commented Mar 2, 2019 at 6:51

1 Answer 1


"Aurora" in Latin means "dawn", as opposed to "sunrise" (which is "ortus solis", the rising of the sun). This would mean, more or less, the period at which the sky was visibly bright.

The reason for selecting this time was undoubtedly so that Mass would not fall before celebration of Lauds, that part of the Divine Office which was intended to open the day. According to the Catholic Encyclopedia, "The office of Lauds was supposed to be recited at dawn." It seems likely that this general directive could be interpreted differently by various priests, and surely some priests celebrated Lauds quite early in the morning. Hence the directive in the 1917 Code made sure that no matter how early Lauds was celebrated, Mass would come after it. (In convents or monasteries which celebrate the Divine Office, the first Mass of the day is often celebrated immediately after, or at least very shortly after, the end of Lauds.

  • So we need a exact defition of "dawn" (my gut feeling says there is one in the older canonical literature). Englisch Wikipedia knows astronomical (18°), nautical (12°) and civil dawn (6° below the horizon). Latin Wikipedia knows (in the stub article Aurora) only the definition 6° below the horizon.
    – K-HB
    Commented Mar 1, 2019 at 21:02
  • 2
    On your explanation: When Lauds were to be reciteted at dawn, why mass shold not be said before one hour before dawn?
    – K-HB
    Commented Mar 1, 2019 at 21:04

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .