Secret of the trunk of Lord Ganesha

Most Ganesha idols are depicted with the trunk turning towards the left. The left side of our body symbolises the feminine side of our personality. It represents the moon. It is cool and relaxed.
The right side represents the masculine aspect, and symbolises the sun – hot, fiery and aggressive.A Ganesha idol having its trunk curved towards the right, is called the ‘siddhi vinayaka’ and needs special worship. It is said that one should be very careful in worshipping such idols. The puja that is performed on such an idol is supposed to be done after fulfilling all religious requirements and by adhering to a strict code of conduct.
According to the nadi system of the human body espoused by Hinduism, there are three nadis or channels which are responsible for overall health - the left channel is called the Ida Nadi and is connected to the right side and the back of the brain. This channel looks after our emotional life and our past.The right side channel is called as the Pingala Nadi. It is connected with the left side and the front of the brain. This channel controls the supraconscious mind. It creates our future.
The Sushumna is the central channel for our evolution. It is through this channel that we become collectively conscious It makes the connection between our conscious mind and the Spirit, which is a reflection of God.According to Hindu mythology, the direction of Lord Ganesha's trunk is related to these nadis. Since the Ida Nadi is on the left side, while the Pingala Nadi is on the right, the left-turning trunk has easy rules and one can do puja without following strict rules, since the Ida Nadi is the moon. But, the right turning trunk is the sun and will burn one, if rules are violated. When the trunk is facing straight, then it signifies that the Sushumna is entirely open.
Another logic is that the idol with a right-sided trunk is called dakshinabhimukhi murti (the idol facing the south). Dakshin means the southern direction .The southern direction leads to the region of Yama (Yamalok), the deity of death.The one who is able to face the direction of Yama's region is strong.Ganapati with the right-sided trunk is said to be 'active (jagrut)'. The ritualistic worship of this idol is performed observing all the norms of ritualistic worship meticulously.
The idol with the trunk towards the left is called Vamamukhi. Vam means the northern direction or the left side. Since the northern direction is spiritually favorable; it bestows Bliss; hence the Vamamukhi Ganapati is more commonly worshipped.