Question : What is the importance of Lunar/Solar eclipse for spiritual practice.
There are certain cosmic events - for example solar eclipse/lunar eclipse, makara sankramana etc. These cosmic events represent significant shift in the cosmic energy pattern. These change in energy pattern has effect on the living and non living being on the earth. For example, during solar eclipse, all birds, animals go into a sort of hibernation. During full moon, some of the psychological disorders aggravate. Cosmic events have effect on conciousness.
Macrocosm and Microcosm relationship ( Brahmanda and Pindanda)
As is macrocosm. So is microcosm. Human body is a microcosmic representation of the macrocosm. It is like seed and tree. See has all the properties of the treee. Human body has 3 channels called ida, pingala sushumna. Ida - means lunar - current influenced by moon. Pingala means - sun - current influenced by sun. Sushumna means - transcendent - Brahmanadi.
Normally state of conciousness involves pranic current flow in ida and pingala. During deep meditation/transcendent state - turiya, current flows in brahmanadi - called sushumna.
During parva kala - auspicious period - solar/lunar eclipse, the pattern of current in ida and pingala are disturbed. Pranic energy starts flowing in Sushumna. This will give an experience of Transcendance - deep meditative state. To experience this - following conditions are required.
a). Regular practice of meditation.
b). Fasting couple of hours before - to ensure that the pranic energy is free. ( eating fruits is ok for people who have physical ailments).
c). Ability to observe current flow/direction, movements in spinal cord.
d). Sensitivity to pranic body.
The parva kala offers a natural opportunity to experience state of liberation. However actual liberation happens due to wisdom with practice of yoga. These external conditions do not apply to a person who is enlightened. These are useful only for sadhaka - spiritual aspirant.