Please give references.
If not, then why do people believe in it, or why is it used in marriage ?
Hinduism Stack Exchange is a question and answer site for followers of the Hindu religion and those interested in learning more about Hinduism. It only takes a minute to sign up.Sign up to join this community
Jyothisha is one of the 6 Veda Angas (auxiliary of Vedas).
It's main purpose is to predict positions of gruhas in space (Astronomy) to determine best time for rituals.
It's secondary purpose is to predict predisposition of people born at a certain time to determine compatibility with another man/woman for marriage (what is commonly known as Astrology or Janma Patrika or Jataka matching)
Today, Jyotisha has a mixed reputation in public because it is confused the with English word Astrology, because 'Astrologers' who did not duly study at a Veda Patashala/Gurukul, started making money by exploiting innocent people with half-baked knowledge and claims e.g. numerology, palmistry, zodiac predicitions etc.
The opportunists (atheist/rational/liberal/anti-Hindu) are also to blame, because they used the above problem to attack the scripture itself. It's like saying 'Modern medicine is bad, because some MBBS-fail doctors prescribed bad medicines'
Jyotish is an exact science. A Vedic pundit in a village in India with a Panchaang (traditional Hindu almanac calendar), can predict exact eclipse times without complicated NASA telescopes.