jyotisha and the sky
What are the nine Grahas in Jyotisha and are they the same as planets?
What the nine Grahas are
Jyotisha, the Hindu system of astrology and astronomy, works with nine Grahas, called the Navagrahas. They are the Sun, the Moon, Mars, Mercury, Jupiter, Venus, Saturn, and two called Rahu and Ketu. Seven of these are visible bodies in the sky. Rahu and Ketu are different. They are the two lunar nodes, the points where the Moon's path crosses the Sun's path. They have no physical form. In the tradition they are described as the head and tail of a serpent, and they are treated as powerful forces even though nothing is physically there.
What the word graha actually means
The Sanskrit word graha does not mean planet. It comes from a root meaning to seize or to grasp. The tradition sees each Graha as something that holds sway over a person's life, health, mind, and circumstances. So the Sun and Moon are Grahas even though modern astronomy calls them a star and a satellite. Rahu and Ketu are Grahas even though they are invisible points. The category is about influence, not about what kind of object something is.
Where the system comes from
The Navagraha system is laid out in Jyotisha texts of the tradition. Each Graha is given a set of qualities, a day of the week, colors, gems, metals, body parts, and areas of life it governs. The tradition holds that their positions at the time of a person's birth shape that person's tendencies and experiences. Rahu and Ketu carry special weight around eclipses, since eclipses happen near the lunar nodes. This is why the tradition treats them as powerful even without a physical body.
How modern astronomy sees it
Modern astronomy uses the word planet in a precise technical sense. By that definition, the Sun and Moon are not planets, and Rahu and Ketu do not exist as objects at all. The lunar nodes are real mathematical points used in tracking eclipses, but they are not things you can see or touch. There is no scientific evidence that the Grahas influence human life in the way Jyotisha describes. The two systems are simply built on different ideas about what the sky means.
Today
Many Hindus around the world worship the Navagrahas at temples, especially before big life events like weddings or new beginnings. Shrines with all nine figures arranged together are common across South and Southeast Asia. Some people follow Jyotisha closely, others treat it lightly, and others not at all. Practice varies a great deal by region, family, and personal belief.