Wouldn't it be wonderful if there was some secret mathematical formula astrologers could use to figure out the Ascendant when there is no birth time? Yes, it would. Unfortunately, despite years of research by many astrologers, myself included, the 'timeless' Ascendant remains out of reach. However, just to be able to discover the Rising Sign itself would be helpful. This is where a very old method called Pre-Natal Lunar Epoch comes in. It's based on the fact that an average pregnancy lasts for 10 Lunar months. This period is 40 weeks - or 280 days. If you know the date on which you were due to be born - not the actual day you popped out - go back 280 days from the due date and check to see which sign the Moon was in. That Moon sign, the sign opposite, or the sign on either side of those two signs, will indicate your potential natal Rising Sign.
If you decide to try out this method, please remember that the six signs you end up with are your possible rising signs. One of them will be that sign and it's up to you to assess yourself honestly before you attempt to decipher which one it is most likely to be. If you ever discover your actual time of birth and are able to calculate your rising sign for real, you might be very surprised. I've encountered this many times when I tell people which sign their Ascendant is in. "No, it can't be!" is a common reaction. I experienced that reaction myself as a student when I first calculated my own birth chart. There I was, Miss Aquarius Sun and Moon - then suddenly I found out my rising sign was Capricorn. "Capricorn?! Nooooooo! It can't be!" But it is. The interesting thing is that the older you get, the more you become like your rising sign, so if it doesn't seem to make sense now, just wait.....