Question

What is the technical term for the difference between a planet's position today and its position tomorrow (i.e., its daily angular velocity)?

• A. Phalam (Result)
• B. Gati (Motion/Velocity)
• C. Kendram (Anomaly)
• D. Savanam (Terrestrial)

Hint:

In physics, "Velocity" is the rate of change of position. In Sanskrit, "Gati" is the word for velocity or movement. Therefore, the difference in position over time is Gati.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
In astronomy, planets are constantly in motion along their orbits. For the purpose of making an almanac (Panchang), astronomers calculate the position of a planet at a specific time, usually sunrise. Since planets move at varying speeds, we must calculate how much distance (angular displacement) they cover in a single 24-hour period.

Step 2: Detailed Explanation:
The term 'Gati' in Sanskrit means "motion," "movement," or "speed." In Siddhanta Jyotish:
- Adyatana Graha: The longitude of the planet at today's sunrise.
- Shvastana Graha: The longitude of the planet at tomorrow's sunrise.
- The subtraction of today's position from tomorrow's position yields the daily motion, known as the Gati.
\[ \text{Gati} = \text{Longitude}_{\text{tomorrow}} - \text{Longitude}_{\text{today}} \]

Step 3: Analysis of Options:
1. Phalam: Refers to a "result" or a correction factor (like Manda Phala or Sheeghra Phala) applied to a mean planet to get a true planet.
2. Kendram: Refers to the angular distance of a planet from its point of highest or lowest speed (Aphelion/Perihelion).
3. Savanam: Refers to the terrestrial day itself, not the movement within it.

Step 4: Final Answer:
The change in position over one day is technically termed as 'Gati'.