Begin this Sun mantra on a Sunday (the day ruled by the Sun), during a waxing phase of the Moon. The ideal time of day to chant a planetary mantra is in the early morning, when all is quiet.
Mantras can be started at any time, however it is best not to start within three days on either side of the dark Moon (New Moon). If possible, start when the Moon is bright and waxing. Some prefer to start mantras on the day ruled by the planet. This is not critical, but for those who want, you may start the Sun mantra on a Sunday.
How to Chant the Sun Mantra
Chant the Sun (Surya) mantra 7,000 times. This need not be done in all one sitting. See the Planetary Mantras page for how prayer beads help with counting, and for more tips.
Pronunciation
Japa koosooma sankarsham kashya-peeyam maha-jutim, tamorim sarva pahpagnam pranato smee deevahkaram.
Let us chant the glories of the Sun god, whose beauty rivals that of a flower. I bow down to him, the greatly effulgent sun of Kasayapa who is the enemy of darkness, and destroyer of all sins.
English translation
Why it Works
This mantra can be seen as a type of prayer that invokes the grace of a planetary energy to lessen its negative effects as revealed in the horoscope.
There are many kinds of astrological mantras. Some are devotional, some are Vedic, and some are Tantric. The mantras given here are mainly devotional. Therefore, while one should be careful to try and pronounce the mantras as accurately as possible, they will still work with individual pronunciations.
For more on how planetary mantras work, see the Planetary Mantras page.