Planets are called Grahas in Sanskrit. According to the Hindu concept there are nine grahas viz. Sun (Adhithya), moon (Soma), Mars (Angaraka), Mercury (budha), Jupiter (Brahaspathi), Venus (Shuka), Rahu and Kethu. The last two of them are called shadow planets. These nine are deities (not planets) in the Vedas. The prayers to these deities occur mainly in Rig Veda and Atharvana Veda. A collection of such relevant prayers along with a ritual beginning is this prayer called Nava Graha Suktha. This is chanted to pacify / attract the nine planets and fulfill our wishes. It is interesting to note that in the prayer, they are not referred to as planets and most of the prayers are addressed to Indra and Agni (fire) who are both very powerful Vedic Gods and not to individual planets. The language and meter used in these Sukthas are in Vedic Sanskrit. Since my knowledge of Vedic Sanskrit is not up to the mark, I have relied on the translation given by RL Kashyap (2007) in Veda Manthras and Sukthas of SAKSI, Bangalore. This translation is my own. The sukthas in Devanagari script are given in lansingtemple.org/navagrahas/prayers/NG%20Suktam.pdf. The text used by me slightly differs from what is given in the web site as I have relied on the text given in the above referred book. I have broken up the lines in to smaller ones while translating so that the meaning is more clear.
Om Nava Graha Suktham
Om Shuklam baradaram vishnum sasi varnam chathur bujam
Prasanna vadanam dhyayeth sarva vignoba santhaye.
Dressed in white you are,
Oh, all pervading one,
And glowing with the colour of moon.
With four arms, you are, the all knowing one
I meditate on your ever-smiling face,
And pray, � Remove all obstacles on my way�.
OM Bhoo, Om Bhuva, Ogum Suva, Om Maha. Om Jana. Om Thapa,
Om thathsa vithurvarenyam bhargo devasya deemahi dhiyo yona prachodayath,
Om AApa, jyothi rasa, bhoorbhuvaswarom
We meditate on the seven upper worlds and the great Mantra Gayathri.
Mamo partha duritha kshaya dwara Sri Parameshwara preethyartham Adithyadhi nava graha namaskaran Karishye.