Hora is the division of the zodiac based on the luminaries, Sūrya) and the Moon (Candra). The entire zodiac is created and sustained by Sūrya and Candra. This is what we know as the ecliptic. This way of dividing the zodiac into two halves is based on the distance of the Sun from the earth. This divides the zodiac along an imaginary line passing through the zero degrees of Leo and zero degrees of Aquarius giving the two halves. The half or hora is derived from two words – “Aho” meaning day and “Ratra” meaning night. Thus, the division of the zodiac was into two parts called the solar and lunar halves. The parampara also terms this as Sūrya hora and Candra hora respectively.

आद्यन्तवर्णलोपाद्योर सिद्ध्यत्यहोरात्रात्। तत्प्रतिबद्धश्चायं ग्रहभगणश्चिन्त्यते यस्मात्॥ २-२ ādyantavarṇalopādyora siddhyatyahorātrāt| tatpratibaddhaścāyaṁ grahabhagaṇaścintyate yasmāt

Translation: The word ‘Horā’ is derived from the word अहोरात्र (ahorātra). The first part of this word अहो (aho) means day or sunlight period and the second part of this word रात्र (rātra) means night. By removing the initial letter अ (a) from the first part and last phoneme त्र (tra) from the second part we obtain the new word होरा (horā). The solar half or Sūrya hora included the six signs in the zodiacal or clockwise order from Leo to Capricorn and the lunar half or Chandra Hora included the six signs from Cancer to Aquarius in the reverse or anti-clockwise order. The Sun and Moon own adjoining signs (i.e. Leo & Cancer respectively) in their Hora’s while the five other planets in the order of Mercury, Venus, Mars, Jupiter and Saturn (based on their geographical distances from the Sun i.e. Mercury is closest and Saturn is the most distant) shall own the signs in their proximity to Leo (and Cancer) reckoned in the zodiacal (or reverse) order
Hora based on the solstice – The Maharishi’s also observed the two solstices’ where the length of the day (i.e. daylight duration) was the longest and shortest respectively called the summer and winter solstice. The Summer solstice is the longest day and marked the end of the hot summer season and the beginning of the rainy season. So also the winter solstice marked the end of the long nights. Thus, the zodiac was divided into two halves along an imaginary line passing through the Zero Degrees of Cancer and Zero Degrees of Capricorn, which showed the position of the Sun at these two extreme points of the longest day and longest night. This formed the two Ayana or halves of the zodiac comprising three seasons each. The specific terms used are Uttar-Ayana or Northern Goal and Dakshin-Ayana or Southern- Goal and refers to the ‘goal’ of the Sun as it seeks to reach the northernmost point of the zodiac (i.e. Zero degrees of Cancer) or southern-most point (i.e. zero degrees of Capricorn). This can also refer to the goal of seeking the northernmost latitude, which coincides with the summer solstice, or the southernmost latitude, which coincides with the winter solstice