Question
What is Mangal Dosh (Mangalik)
Answer
In the lagna kundali (birth chart with the ascedant) of a person if any malefic planet (especially the planet mars) is present at least in the lagna (1st house) or in the 7th house (house of the spouse or marriage) then the person is considered to be a mangalik. Other houses that are considered for mars's presence for a person to be mangalik are 2nd, 4th, 8th and 12th.
If Mars be posited there, she will become a widow, both benefics and malefics occupy the 7th house, she will remarry. If there be a malefic or malefics in the 8th house, she will get a shortlived husband. If the 2nd house is occupied by malefics, the native dies with her husband. [Phaladipika, Chapter 11]
Mars being firey in nature when it looks upon the house of marriage or partner, it is said to burn that house. Hence, it creates tension, quarrel, etc. among the partners and even affects the health and life of the spouse of a mangalik person. So if one of the partners has magalik dosh marriage is discouraged. If both partners have the fault, then it gets canceled out and marriage is ok.
However, sometimes Kumbh Vivah is performed because it makes the banayan tree, peel tree, etc. the first husband and then it has to suffer the bad consequences of the mangalik dosh, not the actual husband. Vishnu being God Himself, it is believed mars can't have -ve effects on Him.
Disclaimer: I have provided the answer only as per my awareness about astrology, I am not an expert.
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