In natal astrology, a natal chart is a horoscope/astrological chart drawn for the exact time of an individual's birth at a particular place on Earth for the purposes of gaining information about the individual. Commonly used alternate names for the natal chart include birth chart, natus, nativity, radix, and genethliac chart, among others.
In addition to the date of birth, an accurate birth time (the first breath is generally agreed upon as the exact time when the chart should be calculated) and a location are essential when calculating a natal chart so that the primary chart angles may be calculated with the greatest possible accuracy. These include the ascendant (or "rising sign"), imum coeli, descendant, and the midheaven.
The picture to the above-right is a modern example of a natal chart as a modern Western astrologer would most likely view it (though there are variants depending on the specific astrological tradition that the astrologer follows and/or their personal preferences). The design, along with the symbols/glyphs used in the chart, can vary widely; some choose to include the Zodiac wheel, while some do not. Also, charts do not have to be round -- following the Hellenistic/Roman, medieval and/or Vedic styles, they can be square as well.
The astrological aspects (such as conjunctions or oppositions, among others) are delineated in the center of the chart. The twelve signs of the Zodiac are located at the outer portion of the chart wheel; similarly, twelve segments of arc form astrological houses which are said to have significance for different areas of life. There are many different systems for calculating the houses. The sample chart uses a quadrant house system of house division whereby the angles of the chart divide the chart into four quadrants with three houses within each quadrant, and in which the houses usually include portions of more than one astrological sign. Each quadrant has an angular house, which includes one of the angles of the chart; a succedent house follows this, with a cadent house at the end of the quadrant.
The time of birth can usually be found on the birth certificate in many countries. In some instances, however, the birth times are rounded off by the nurse or doctor that is present to the nearest half or quarter-hour, thus rendering the time only approximately correct. Because of this fairly common practice, the parents should always remember to note the exact time of the child's first breath and not rely on the time given on the birth certificate in the event that they ever plan on having a precisely accurate natal chart calculated for their child. An accurate time of birth is virtually useless if the exact location of birth is not known.
Most charts are geocentric, that is based on the Earth. However, there is no reason in theory why a chart cannot be created for another planet. Some astrologers use Heliocentric - Sun centered - charts which only require an accurate time as the location would be the Sun. These are theoretical constructions and have a different interpretation to geocentric natal charts. Charts based on other planets would need all the points recalculating from that point of view; for example, "Jovocentric" would be a Jupiter centered view.
Once the astrologer has ascertained the exact time and place of the subject's birth, the local standard time (adjusting for any daylight saving time or war time) is then converted into Greenwich Mean Time or Universal Time at that same instant. The astrologer then has to convert this into the local sidereal time at birth in order to be able to calculate the ascendant and midheaven. The astrologer will next consult a set of tables called an ephemeris, which lists the location of the sun, moon and planets for a particular year, date and sidereal time, with respect to the northern hemisphere vernal equinox or the fixed stars (depending on which astrological system is being used). The astrologer then adds or subtracts the difference between the longitude of Greenwich and the longitude of the place in question to determine the true local mean time (LMT) at the place of birth to show where planets would be visible above the horizon at the precise time and place in question. Planets hidden from view beneath the earth are also shown in the horoscope.
The horoscope is then divided into 12 sectors around the circle of the ecliptic, starting from the eastern horizon with the ascendant or rising sign. These 12 sectors are called the houses and numerous systems for calculating these divisions exist. Tables of houses have been published since the 19th Century to make this otherwise demanding task easier.
Chart shaping involves assessing the placement of the planets by aspect and position in the chart, and noting any significant patterns which occur between them. This involves noting significant aspect patterns (or groups of aspects), which may appear in the chart and any other patterns , such as Jones patterns.
Although the solar chart is deficient in that it cannot show the ascendant, midheaven or the houses with any accuracy, it can neverthelss provide a fairly accurate profile of a person's character from examining the position of the planets alone.