Question

What is the main problem with a calendar based on the Moon's orbit around the Earth?

A) The Moon's orbit is elliptical, so the Moon moves faster at perigee than at apogee.
B) Some years would have to have 13 months, while other years would have 12 months.
C) The Moon is not visible every day of the month.
D) The Moon's orbit is tilted 5 degrees to the plane of the ecliptic.

Answer 1

The main problem with a calendar based on the Moon's orbit is the irregularity of month lengths, requiring some years to have 13 months and others to have 12 months. Therefore correct option B.

Step-by-step explanation:

A challenge in a lunar-based calendar arises from the necessity for some years to contain 13 months, alternating with others having only 12 months.

The lunar month, which is the time it takes for the Moon to complete a full cycle of phases, is approximately 29.5 days. If a calendar were strictly based on the Moon's orbit, it would be challenging to synchronize lunar months with the solar year (the time it takes for the Earth to complete one orbit around the Sun), which is about 365.25 days.

As a result, a lunar calendar would likely need to insert extra months periodically to align with the solar year, leading to irregular month lengths and causing some years to have 13 months, while others have 12 months. This inconsistency in month lengths would complicate long-term planning and make the calendar less predictable.