When Sun is located in Aries, it then acquires the cardinal characterized and it is in more harmony to its true nature. It can then manifest all its power and fire in a positive and focused manner. But when it is in Libra, the Air element of Libra makes it completely unfocussed and the fire is totally out of control and it does not produce anything.
So Aries is its sign of Exaltation and Libra is its sign of debilitation. Hence coming back to our original question, the planet is strong and beneficial for us in our chart provided it is in its own sign and it is even better if it is in its sign of exaltation.
It is worst for us if it is located in the sign of debilitation. If the planet is in any other sign, the general rule is the planet will have mixed result something between its best result and its worst result.
However we can make further distinction about the nature of planet in our chart in other signs by analyzing the relationship of the planet with the ruling planet of the particular sign where it is located.
This brings us to yet another concept in Vedic astrology.
The relationship between different planets in our chart:
First we shall talk about permanent and natural relationship between two planets irrespective of their position in the chart.
The planets can be broadly classified into two groups:
The first group:
In this group belong the following planets:
Sun, Moon, Mars and Jupiter.
The second group:
Mercury, Venus and Saturn.
The general rule is the planets belong to first group are harmoniously disposed to each other and they are permanent friends to each other. Similarly the planets belong to second group are generally friendly to each other and are harmoniously disposed to each other.
However each planet in first group is considered to be permanent enemies of the planets belonging to the second group or they are not harmoniously disposed to each other.
The first group of planets is generally responsible for creative functions in our life internally and externally.
The second group of planets is generally responsible for destruction and decay in our life function both externally and internally.
We must not forget that in life as in nature both the creative function as well as the decay function is necessary to create the balance in nature. Both are necessary.
However the actual classification of permanent planetary relationship and its specific scheme for chart analysis varies a little from this general classification and is given below.