Birth time
What if you don't know the time?
Two Skies can be done even if one of you, or both, does not know the birth time. The price is the same.
If only one of the times is missing, the houses, the Ascendant and the Midheaven of the person who knows it remain, and the other person's planets are still read in those houses. What is lost: the houses, Ascendant and Midheaven of the person who does not know their time, the Ascendant, Midheaven and houses of the composite chart and, in the Complete edition, that person's hour pillar of the Ba Zi. The Ascendants block of the synastry by dimension keeps only the Ascendant that is known.
If both times are missing, the houses, the Ascendants and the Midheavens of both charts and of the composite are lost, as is the Ascendants block.
Either way, the Moon moves about 13° a day, so the Moon of whoever does not know their time has an approximate position: its aspects are marked as uncertain and, on some days, the sign itself remains open. The aspects between the other planets, which make up most of the synastry, nearly all remain, as do the numerology and the symbolic traditions. The report always tells you what has been left out.
With an approximate time (up to 30 minutes either way), everything is included, but the Ascendant is no longer a single point. In 30 minutes it can move 15° or more, so it comes as a range of degrees, as does the composite's, and, if the range crosses from one sign into the next, with both signs. The Midheaven follows the same rule. Contacts to the Ascendant are listed as to be confirmed, each with the time at which it would occur: for example, "if Ana's time is closer to 14:00, Bruno's Venus touches her Ascendant". The report does not pick any of those times as the right one. The houses are marked as indicative where the margin does not change them and, where it does, given with the possible houses. In the Ascendants block, contacts to the Ascendant of the person with an approximate time move to that to-be-confirmed list.
The time is often on the full (long-form) birth certificate, which you can request from the civil registry, in an old baby or health record, or in family memory.