Short answer: not exactly. The rising sign (ascendant) is the zodiac sign on the eastern horizon at the moment you were born, and the horizon sweeps through the whole zodiac once a day. That is a new sign roughly every two hours. Without a time, there are twelve candidates.
Why the time matters so much
The Sun moves about one degree a day, so a date pins it down. The Moon moves about thirteen degrees a day, so a date nearly pins it down. The ascendant moves about 360 degrees a day. Being an hour off can change it; being four hours off certainly will.
Where to find your birth time
- Your birth certificate (long form). In many countries the time is on it; in some it is not.
- The hospital record or the baby book: parents often wrote it down.
- Family memory, which is usually good to within an hour (“just before dinner”).
What you can still read without it
Quite a lot. Your Sun sign, your Moon sign (except on the roughly one day in three when the Moon changes sign, and then it is one of two), Mercury, Venus, Mars and the slow planets, the Moon’s phase at your birth, and the balance of elements. A good reading simply leaves the rising sign out and says so, rather than guessing.
If you know it roughly
“Morning” or “evening” narrows the ascendant to a few signs. A trick: at sunrise the rising sign is your Sun sign; by midday it is about three signs later; at sunset it is the sign opposite your Sun; around midnight it is about three signs before your Sun. If you were born “around sunrise”, your rising sign is very likely your Sun sign.
Rectification
Astrologers sometimes work backwards from life events to estimate a birth time. It is slow, expert work and still an estimate; treat any rectified time as a guess, not a record.
Read your chart with or without it
The Night You Were Born works both ways: with a time it draws the horizon on the wheel and reads the rising sign; without one it reads everything else and tells you when the Moon is uncertain. Get it on Etsy.