Selûne (moon)

Selûne was the name of Toril's moon.

Description
Selûne was about 2,000 miles across and was located some 20,000 miles away from Toril. To an observer, it appeared about the size of a human fist held an arm's length away. It was quite bright on a clear night, able to cast pale shadows.

Selûne was followed in the sky by the Tears of Selûne, a constellation of very small celestial bodies (often identified as nine stars, but in reality hundreds of asteroids).

Eclipses
Due to the size and relative rotation of Selûne and Toril, eclipses were quite frequent and commonplace.

Lunar phases
Selûne was full at midnight on Hammer 1, 1372 DR, and subsequently every 30 days, 10 hours, and 30 minutes. Selûne was also full at midnight on the first day of every leap year. Selûne made exactly 48 synodic revolutions every four years, so the phase of Selûne is the same at the same time on the same date every four years. Selûne is generally full around the first day of each month, give or take a day; festival days serve to keep the moon's phases consistent across calendar months and years.