मङ्गल means auspicious but Mangal is considered as papa graha in astrology. Why is that, does anybody know the explanation?
The whole concept of papa graha is misleading, it makes people think that if there is a papa graha it destroys the native. But it is not like that. Every planet can be problematic if it does not get a proper place in chart.
Mangal Although a papa Graha, its effects on ones life depends on its postion in the chart. Mangal gives marriage, 'sobhagya' etc. If its correctly positioned in a chart it benifits the Native.
Mangal shows Husband in specific, if placed wrongly it might make the women widow or may show signs of divorce etc. Mangal placed correctly does not affects things and might give a very good husband. It also gives property, land, confidence, rights, leadership etc. Remember it depends highly on position in chart as well as other aspects.
It has the ability to give auspiciouslity as well as take it away. So we call many things with a 'mangal' in them like 'Mangal krya', 'magalmay', 'magalsutra' etc.
Note: I am answering from a personal point of view. Someone else might give a diffrent opinion or if possible a reference from some text.