Although the sign in which the ascendant is situated could be said to be the ascendant sign, the ascendant will not be present in the entire sign. The degree, minute and second in the sign is the ascendant. The ascendant longitude is said to be the first house. The extent of ascendant longitude is 15 degrees to its front and 15 degrees to its back, altogether 30 degrees. When we add 15 degrees to the ascendant longitude we get the last part of the ascendant house and when we calculate 15 degrees backwards we get the first part of the first house. The ascendant longitude is the middle of the ascendant house.
Eg: Suppose that the ascendant longitude is 10 degrees 15 minutes in Mesha. When we take 15 degrees ahead, we get Mesha 25 degree 15 minutes. When we take 15 degrees back then what we get is Meena 25 degree 15 minutes. Thus, the ascendant house is from Meena 25 degree 15 minutes to Mesha 25 degrees 15 minutes. From the 30th degree at the end of the first house the second house begins, then at the 30th degree from there the third house begins and in this order, the 12 houses are formed.
Bhava Sandhis or house cusps
Bhava sandhi is the meeting point of two houses. The planet in Bhava sandhi is passive. The planetary conjunctions in the zodiac may not be exactly repeated in the houses. Changes can be brought in according to the longitude of planets.
Eg: Suppose the ascendant is Mesha. Jupiter and Moon have been shown there. In the 12th sign of Meena, Venus and Mercury have been shown. Here, the ascendant longitude is 0 sign 10 degrees 15 minute. The longitude of Jupiter is 0 sign 28 degrees 10 minute i.e. Jupiter is situated in Mesha 28 degree 10 minutes.
Moon longitude is 0 sign 3 degree 12 minute i.e. Moon is situated in Mesha 3 degree 12 minute. The ascendant house is on the other hand; Meena 25 degree 15 minutes to Mesha 25 degree 15 minutes. Since Jupiter is placed on Mesha 28 degree 10 minutes, this is after the first house i.e. in the second house. Moon is in the first house at Mesha 3 degree 12 minute. Since the house begins at Meena 25 degree 15 minutes, Moon is in the ascendant house itself.
In the zodiac, the Jupiter and Moon be shown in the Mesha sign. Still, as per house, Jupiter is in the second house and Moon in the first. Mercury and Venus are marked in the Meena sign. As the beginning of the first house is at the end of the 12th house, Kumbha 25 degree 15 minute to Meena 25 degree 15 minute constitutes the 12th house. If the longitude of Venus is at 11th sign 25 degrees 20 minute and that of Mercury is the 11th sign 10 degrees 15 minute, then Venus is in the ascendant house and Mercury in the 12th house. The Venus, which is shown in the 12th house in the zodiac, is in the ascendant house according to the house, and Mercury is in the 12th house itself. (See the Planetary dispositions in the zodiac and the house)