Chandra Puja is to appease the planet Moon. Chandra Puja is very useful & beneficial puja, since it's worship strengthens benefic Moon & increases its positive influence and pacifies malefic effects of the planet & neutralizes its negative effect. Chandra Puja is recommended for those having malefic Moon or wrongly placed Moon as per horoscope.
The planets are to propitiated against their evil influences, to ward off them, the Moon Puja is done with faith to ward off all evils of Moon as per the horoscope. Chandra Puja is dedicated to Lord Chandra, the Moon God. Grah Shanti Chandra Puja (Moon Worship) is recommended to those, having malefic Chandra or wrongly placed moon as per the horoscope. Chandra gives a calm and soothing affect to our life. Moon is the ruler of mind and all the senses are controlled by the mind