Astrology is a science of similarities. This principle of Astrology is to be understood in detail to know how the significations of everything have been arrived.
We take Sun as Significator of father (leading member of family), Prime Minister, King, President, Chief Minister etc. This is because all the planets have taken birth from the Sun & life on Earth can not be thought of without Sun.

Similarly Moon is siginificator of mother, emotions, liquids, all liquids etc. because it transfers sunlit to Earth, is cool & attracts liquids (effects of Moon on Sea & Oceans).Mars signifies aggressiveness, soldier, blood, arms etc. because it is red in colour. Mercury is very small & always remains close to the (father) therefore it is considered as "Prince" in the planetary cabinet & signifies students, youngsters, dependents, education, intellect etc. Venus is most beautiful planet therefore it signifies luxuries, beauty, comforts etc. Jupiter is the biggest of all the planets therefore it signifies respected people e.g. teacher, preacher, gurus, saints, rishis, elders of the society.Saturn is far off planet, cold & slow ; therefore it signifies old, outcast etc.Rahu & Ketu eclipse even the strongest luminary, Sun & do not posses any body.

They are shadowy planets therefore they signify disguised things, outcast & things not fit in social norms. Uranus is a planet, which signifies revolutions. The key word for Uranus is therefore revolutions. Uranus signifies all revolutions, revolutionary ideas or movements.

Neptune is psychic & therefore arises confusions among people. It signifies all confusions that results wars or wrong steps. Mars is a soldier & can kill, whereas Pluto believes in mass killings. Therefore mass destruction emerging out of earthquakes, cyclones, atomic explosions etc. & these phenomenon are signified by Pluto.