Every field, or branch of studies, has a few strengths and drawbacks. Vedic Astrology, or Hindu Astrology, is a modern nomenclature for "Jyotisha" - which in Sanskrit implies the study of light (Jyoti).
Compared with the Western or Hellenistic form of astrology, Vedic Astrology is a completely different system of approximation and prediction, because it provides utmost importance to the Moon. The Moon represents our mind, emotions, and instincts. Being the nearest celestial body to the Earth, it is indeed a powerful influence - and there is no point in meaningless debates of right or wrong. This method of calculation works, and in certain areas, its concepts and methods are adopted into modern form of astrology.
Apart from the very concept of Ascendant, that is the same as "Lagna" in Vedic Astrology, there are other concepts that stand unchallenged. The most important of them being:
- Nodes of Moon: Adopted from the concept of "Rahu" and "Ketu";
- Grinding Phase of Saturn: Adopted from "Saade Saati", the 7.5 years of Saturn's ultimate tests and challenges;
- Adversely Posited Mars: Adopted from "Mangal Dosha". There are other adverse positions, like the Serpentile ("Sarpa Dosha", also referred as "Kala Sarpa Dosha" or "Naga Dosha").
Other praise-worthy concepts are the system of Lunar Mansions ("Nakshatras") and Compatibility Checks through Composite Charts ("Kundali Milan"), which are vastly neglected due to other accurate methodologies in Western/Hellenistic Astrology.
When compared with the Western or Hellenistic astrology, Vedic Astrology varies in calculations, and even dates of the Signs (Rashis) and transits because it is based on the elliptic of the Moon around the Earth, and not the elliptic of the Sun. With time, it has become faulty - especially because the Moon has been moving away from the Earth - as it slows down, due the obvious conservation of angular momentum. As it happens over the ages, the difference has become substantial. Also, when the system originated, planets like Uranus, Neptune, Pluto, and other significant asteroids were unknown to Mankind, and they remain unconsidered. It is unfortunate that such a wonderful system remains un-updated.
Another disadvantage of the Vedic Astrological system is its usage of Sidereal time, as opposed to the regular Solar time, or Synodic time. Sidereal days are slightly shorter than the Solar Days, by approximately 4 minutes. More appropriate or less appropriate is a matter of debate, but using the Sidereal timeframe requires a revamp of all conventional standards that the entire world unanimously follows. As above, this system remains un-updated, too.
Similar to the huge contribution that the Ancient Indian or Hindu techniques make to Modern Astrology, some of the Ancient Arabian concepts find dominant presence in today's astrology. In Ancient Arabian techniques, much like the system of Lunar Mansions (Nakshatra), various points are calculated in an individual's Birth Chart known as parts. The most commonly used is the Part of Fortune (also referred as Pot of Fortune, or Fortuna).