**Lu****nar Days**

Thithis (Lunar days) are based on the distance of Moon from Sun. Sun’s orbital path is the ecliptic. Other planets have different orbits. We are aware that the paths of all planets are almost identical with that of Sun. New Moon occurs, the luminary Moon is in conjunction with Sun, which means they are at the same point of the zodiac. When the luminaries are 180 degrees away, it is Full Moon. In short, if Moon is approaching the Sun, it is waning (Krshna Paksha). If it is moving away from the Sun, it is waxing (Sukla Paksha).

__
To calculate the
lunar day__:

Find the distance of Moon from Sun. If Moon’s longitude is more than 180 degrees, subtract 180. Divide the distance by 15 and the quotient + 1 is the number of the Lunar Day.

For instance, if Sun
is in Virgo 22 and Moon is in Aquarius 14. Moon is 142 degrees away
from Sun (314 – 172). When we divide 142 by 15, the quotient is 9.
So, it is the 10^{th} lunar day of the Brighter Half (Sukla
Paksha), called Dhasami (9 + 1).

If Sun is in Scorpio 10 and Moon is in Leo 16, the distance of Moon from Sun is 276. 276 – 180 = 96. Dividing 96 by 15, we get the quotient 6. Therefore, the thithi is 6 + 1 = 7, Sapthami (Darker Half or Krishna Paksha).

__
Importance of the
lunar day__:

Lunar day is considered for Muhurtha or fixing time for auspicious events. Certain lunar days are auspicious and others are bad depending on the event. Generally, Prathima (the first), Ashtami (the eighth) and Navami (the ninth) are avoided for all occasions. In North India, Navami is not considered as bad.

-------------------------------------------------------------------------------