सिद्धान्तशिरोमणि: गणिताध्याय (भास्कराचार्य - ग्रहगणित, मध्यमाधिकार व स्पष्टाधिकार सटीक)

69 of the Moon, however a multiplier 20 also is used in addi- tion to 100000, because he has such a quicker motion. Verses 25, 26. To obtain the mean daily motion of the planets. The number of minutes of arc moved by a planet per day gives the mean daily motion of that planet. Though, however, the spatial velocity of each planet is the same per day, in angle, the velocities differ, (on account of the varied distances) and so we perceive slowness or fastness in the movement of the planets. Comm. Easy. The assumption of equal daily spatial velocities for all the planets has been explained before. The daily angular velocity of a planet in minutes of arc is R × 360 × 60' ─────────────── where R is the number of its sidereal re- M volutions and M the number of mean solar days in a Kalpa. Verse 27. The reason for unequal angular velocity of the planets. Since the planetary orbits are all construed as com- prising of 360° alone, a minute of arc of a smaller orbit has a smaller spatial distance which will be covered more rapidly, the velocity being constant, whereas of a longer orbit, a minute of arc means a longer distance which will be covered in a longer time at the same spatial velocity, which means that the planet appears to be slow in motion. Thus the Moon, the Mercury, Venus, Sun, Mars, Jupiter, Saturn being placed at longer distances from the earth in ascending order their orbits are longer in ascend- ing order so that they are slower in angular motion in that order. Here ends the section called Pratyabda Suddhi in the chapter Madhyādhikāra.