A lunar month can only be 29 or 30 days long. This is different than a solar based calendar, where the length is arbitrarily fixed.

The crescent moon's visibility depends on several factors that impact its rotation around the earth:

• moon's age
• moon's angle from the sun
• moon's altitude above the earth's horizon
• time lag between sunset and moonset, etc.

Lunar Phases for a 29 day month

Lunar Phases for a 30 day month

The difference between these two images is the fact that Mahaq is one night or two nights, depending on visibility factors.