Astronua

Rising sign calculator

Calculate your rising sign (ascendant), its degree and your chart ruler from your birth time and place, and see between which hours this sign was rising on your birthday.

The rising sign changes roughly every two hours, so enter the time to the minute.

We find the location from the district, province and country, then add the latitude, longitude and the time zone in force on that date (including daylight saving time).

Enter coordinates manually

If the place can't be found, enter the latitude, longitude and the UTC offset at the time of birth. When these are filled in, they are used instead of the place names.

Your birth date, time, place and name are stored only in this browser and are never sent to our server.

How is the rising sign calculated?

  1. Local sidereal time

    The Greenwich sidereal time at birth is calculated, and the longitude of the birthplace is added to find the local sidereal time (RAMC).

  2. Ecliptic and horizon

    The point where the eastern horizon crosses the ecliptic is found with a trigonometric formula using latitude and the obliquity of the ecliptic.

  3. Chart ruler

    The ruler of the rising sign is also the ruler of the whole chart; for example, a Virgo ascendant's chart ruler is Mercury.

  4. Rising window

    The moments when the same sign starts and stops rising are searched around the birth time in two-minute steps.

ASC = atan2( cos RAMC , −(sin RAMC · cos ε + tan φ · sin ε) )
ε: obliquity of the ecliptic, φ: latitude

Why does the rising sign matter?

The rising sign is the start of the first house; it describes your appearance, first impression and approach to life. All the houses in your birth chart begin from it. An error of a few minutes in the birth time can change the result if the ascendant is near a sign boundary.

Frequently asked questions

My birth time isn't exact. What happens?

The window shown in the result is the time range during which the same sign was rising. If your birth time falls in this range, the result doesn't change.

What about people born near the poles?

At very high latitudes (above 66°) some signs rise very fast or not at all; the calculation can become unreliable.

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