A horoscope has four primary angles. They include:

  1. First House (Ascendant – East Angle)
  2. Tenth House (Midheaven or M.C. – North Angle)
  3. Seventh House (Descendant – West Angle)
  4. Fourth House (Imum Coeli or I.C. – South Angle)

The ascendant is the sunrise position where the skline and ecliptic interconnect; the ascendant and the midheaven are thought of as the most key angles in the horoscope by the broad majority of astrologers. Majority methods of house division, the ascendant is the point of the 1st house and the midheaven is the point of the 10th house. The positioning of the planetary ruler of the ascendant, called the chart ruler is also thought to be significant. The cusp in the west diametrically opposing the ascendant is referred to as the descendant, usually the point of the 7th house; and the cusp of opposing the M.C. is the point of the 4th house, the northernmost cusp of the map, known as the imum coeli or I.C.

In making a horoscope the ascendant is conventionally positioned at the "nine o'clock" cusp on the left side of the chart wheel. During the development of a day, because of the Earth's revolution, the entire sphere of the ecliptic will pass through the ascendant and will be progressed by about 1°. This motion gives us the words rising sign, which is the symbol of the zodiac uprising over the eastern skyline at the time of birth. The cusp on the ecliptic that is farthest above the plane of the skyline at the moment is called the Midheaven, or medium coeli (M.C.), positioned at the "twelve o'clock position" successfully where the Sun would be if the birth moment was midday.