Marana karaka Sthana, The name signifies a death significating place or house in horoscope.
This is a very common term in vedic astrology and it is also known as Maraka Sthan in astrology. It is a particular house where the planets become extremely weak and dead like. So they are unable to provide any good effect. Every Planet has their own natural significations and in the same way each house is also having certain significations. There are certain house where the planets are very uncomfortable and unable to function properly due to the conflict of natural significations of planets and houses. For example saturn in 1st house, Mars in 7th house etc.
Note of Caution: Before coming to any conclusion on basis of Marana karaka sthana, please do check the Shadbala of planets, conjunction with malefic and benefic planets and aspect.
Now Lets see which are the Marana karaka sthana for each planet and their effect
Saturn: 1st house is the Maran Karak Sthan for Saturn. 1st house is the house of good physical health, creativity and overall fortune. Saturn is the significator of death and disease and sins. It is the ruler of Karma. It cleans up our past deeds and for Karma cleanup,1st house is not an ideal position. Saturn is all about discipline, truth, karmic backlogs etc. so saturn is very uncomfortable in 1st house. It fails to give any good result.
Mars: 7th house is the Maran Karak Sthan for Mars. 7th house is the house of marriage, sex and partnership. The natural significator for seventh house is Venus. Mars is a Warrior. It is a Agni Tattwa Planet. So when a Military and aggressive planet is asked to contribute in Love and romance it becomes very uncomfortable. So when Mars is in seventh house, it gives ill result during its dasha and antardasha.
Rahu: 9th house is the Marana Karaka Sthana for Rahu. 9th house is the house of dharma and spirituality. But Rahu is all about Materialistic gain. It is a immoral planet. So when it goes to the house of morality, ethics it becomes very uncomfortable. SO it gives problems in its dasha and antardasha.
Venus:6th house is the Maran Karak Sthan for Venus. Venus is the planet of Love, Romance, Happiness in our life. It want to live a luxurious life. But 6th house is the house of service, charity, disease etc. So Venus becomes very agitated and uncomfortable here. It fails to give good result. The natives who have Venus in 6th house , generally suffers in relationship.
Mercury: The 7th house is the Maran Karak Sthan for Mercury. Mercury is the planet of learning, Logical expression etc. 7th house is the house of intimacy and romance. But Mercury is a neuter planet. It is neither male nor female. It is not completely matured to understand relationship. So it do not have any role to play in the house of marriage. So it becomes uncomfortable here.
Moon: 8th house is the Maran Karak Sthan for Moon. Moon is the Mind and emotions. Its all about our feelings. 8th house is the house of death. It is the house of occult knowledge, separation etc. Sensitive and soft Moon becomes very uncomfortable in this tough house. From the point of muhurta also chandra asthma is very inauspicious.
Sun:12th house is the Maran Karak Sthan for Sun.Sun is the King. It is our soul. It is a creative planet. But 12th house is the house of Loss, renunciation. The last thing a king will want to give away his kingdom and wealth. So Sun is not happy in 12th house. It gives problems related to health, parents profession etc.
Jupiter: 3rd house is the Marana Karaka Sthana for Jupiter. 3rd is the house of courage and activity. Mars is the significator of this house. Jupiter is the planet of learning, wisdom and spirituality. when he is asked to become aggressive and take weapon in hand, he becomes very uncomfortable.
If any one does have anything to add regarding Maran karak Sthan, please feel free to comment.