Seven main planets rule seven days of week

The seven main planets rule the seven days of the week.

1. Sun rules Sunday.
2. Moon rules Monday.
3. Mars rules Tuesday.
4. Mercury rules Wednesday.
5. Jupiter rules Thursday.
6. Venus rules Friday.
7. Saturn rules Saturday.

http://en.wikipedia.org/wiki/Week-day_names

Rahu and Ketu (Dragons Head and Tail)do not rule any day but Influence Sun and Moon