Sun is never malefic but Cruel, Moon with low Paksh Bal is considered Malefic. Mercury with Malefics that is with Mars, Saturn or Pakshaless will be Malefic.

If the Sun is in the 3rd house, the native will be brotherless (no younger brothers) and his elder brothers will not survive. In the 4th, 5th, 8th and the 12th years he will suffer from physical troubles.

If the Sun is associated with a malefic, the Native will do cruel deeds. He will have two mothers and will be valorous because when the Sun alone will deny younger brothers (vide Sutra 33, how can he with association of a malefic give two brothers). He will be a brave fighter. He will have a good reputation and will enjoy his wealth.

If the Sun is associated with a benefic, the brothers will prosper.

If the Lord of the 3rd house is strong, the brother will be long lived.

If the Sun is associated with a malefic and is also aspected by a malefic the family will be destroyed . If the Sun is aspected by a benefic (and has no malefic influence) there will be growth of family and the native will be wealthy, will enjoy good life and will be happy.
[Brighu Sutras, Sun in the 3rd house]
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Saturn and Sun collided in Leo on Sept 3rd, 2008. Perhaps this is because the Sun and Saturn only collide in Leo, (home of the Sun) every 30 years.

Sun represent government or father. Its nature is dominating, argument and symbol of authority. Sun's direction is East.
Exalted at Aries, 10 degree. Mool Trikon at Leo 20 degree.

If Favorably placed Sun brings fame and power to a person in all areas including the field of occupation. Sun can grant great political power.
If adversely placed, Sun can make a person look arrogant and also may cause mental and emotional disorders. Pessimistic attitude and humiliation at the hands of others become way of the life. It also promotes jealousy in native, if adversely placed.

Sun in Various Houses
The Sun provides better to good results if placed in 1, 2, 3, 4, 5, 8, 9, 11 and 12 houses. The 6, 7 and 10th are bad houses for the Sun.

House No 1 is the perfect House, the permanent House and the House of exaltation of the Sun, whereas the 7th House of debilitation.
The Mars in the 6th House and Ketu in the 1st House make the Sun produce results of an exalted planet.

If the Sun is exalted or placed in an auspicious House of a person's horoscope, he is bound to rise higher and higher in power and position. If obstacles are created against him by a person that person is bound to meet his/her doom.
Much better results are proposed, if the Sun is in conjunction with Mercury.

The Sun gives adverse effects on the things associated with the House in which he is placed. Consequently in the 1st House he will create health problems for the native. In the 2nd House he will affect the family, speech and its comforts absolutely adversely.

The Sun in the 6th House will not prove good for the sisters and daughters for the native and also the health.
In the 7th house he will face obstacles in the comforts of the wife.
The Sun of the 8th House will save the native from death in critical situations. The native will excel in secret science, he will delve on astrology and will try and seek to reach great heights in spiritual attainments.

The Sun of the 9th House will destroy the comforts of the fathers, forefathers and perhaps deprive the native of their properties.
In the 10th house, the Sun will affect the father adversely.
The Sun in the 11th House increases and multiplies the income of the native.
The Sun in the 12th House reduces the comforts of the night hour sleep of the native.

The Sun cannot harm Venus if the Sun is being aspected by Saturn because Saturn and Venus are great friends to each other
But if the Saturn is being aspected by the Sun, then the Sun will not be afraid of Saturn and he will destroy the Venus as both are natural enemies in the house where he is placed.