Rahu & Ketu are not planets, then what?

Zodiac is the belt of heavens limited by lines ofabout 8 degreesfrom the ecliptic on each side. Ecliptic is the path in which planet travels round the sun. But planets do not follow the exact ecliptic.Their paths are sometime along the ecliptic, sometime north of the ecliptic & sometime south of the ecliptic. However they do not swerve to the north or south of the ecliptic beyond 8 degrees.

The distance towards north of the ecliptical line is called northern latitude & the distance towards the south of the ecliptical line is called as southern latitude.

When moon in its orbit round the earth,travels to the northern latitude, the point where it cuts the ecliptic to the north, is deemed a sensitive point known as Northern node of the moon. When it travels to the southern latitude,the point where it cuts the ecliptic to the south, is deemed a sensitive point known as southern node of the moon .These two points, the northern & southern node of the moon are always 180degrees apart

The northern node of moon is called RAHU & the southern node of the moon is called KETU.

thus RAHU & KETU are not planets in the sense of mars, jupiter, mercury etc. they are simply two sensitive points. RAHU & KETU have no mass , no wt, no light, no body . Just for convenience they are referred as planets in hindu astrology.