Lunar Phases Interactive
Lunar Phases Interactive

Lunar Phases Interactive (124.0K)
Everyone is aware that the Moon changes its appearance from day to day. This Interactive will show you why, and allow you to understand how the Moon’s phases are linked to where and when each phase appears in the sky. If it’s sunset, and the Moon is directly overhead, what phase must it be? Is it possible to see the full Moon during the day? What exactly does a “waxing gibbous” Moon look like? Playing with this Interactive will give you a real understanding of how the interplay between Moon, Earth and Sun creates what we see.

The cycle of lunar phases and motions gives us our units of time, such as the hour, week, and month. Lets explore how ancient naked eye observations established them.

 1 What is the length of time from new moon to first quarter? Need a Hint? A) Day B) Week C) Fortnight D) Month

These phases can be matched to the appearance and rising a setting times for the Moon in this cycle, as we shall explore with this interactive and this question.

 2 Which of these sets of phases is the correct order from new to full moon for viewers in the evening sky? Need a Hint? A) Waxing crescent, first quarter, waxing gibbous B) Waxing gibbous, third quarter, waning crescent C) Waning gibbous, third quarter, waning crescent D) Waxing gibbous, full, waning gibbous

As the moon takes about 30 days to circle the sky, each day it moves about 12 degrees on average. Let's see how this relates to civil time keeping.

 3 Given that the moon appears to move eastward about 12 degrees per day as it revolves around the Earth, about how long does it take to move its own 1/2 degree diameter eastward as you observe it. Need a Hint? A) 2 minutes B) 15 minutes C) an hour D) a week

The phase, or synodic month, is 29.5 earth days long. Let's see how this relates to one of the rarer calendar cycles, since our modern months are only loosely based on the original phase cycles.

 4 The modern defination of the "blue moon" is the second full moon of a calendar month. Which of these months can not have a "blue moon"? Need a Hint? A) All months can have a blue moon. B) All months but Feburary can have a blue moon. C) All months with 31 days in them can have a blue moon. D) No month can have two full moons in it.

The cycle of lunar phases gave us our month, and a predictable set of alignments that still today set the Muslim, Chinese, and Jewish calendars, as well as the date of Easter Sunday for Christians. Of these, only the Muslim one makes no adjustments for the solar year, however.

 5 Given the synodic period is 29.4 days, and that the Muslim year is 12 synodic months, how long is this year? Need a Hint? A) 354 days B) 360 days C) 365 days D) 366 days