The Moon and its activity are very popular topics at the Farmers’ Almanac. Things get really exciting around here especially when we have a full Moon. But we know it can be a little confusing for many people with regard to what is actually going on with that giant cantaloupe in the sky. Here’s a “crash course” on understanding the lunar cycle.
Understanding the Lunar Cycle
First, the Moon is on a 30-day cycle when it makes its orbit around the Earth. Actually, the entire trip takes 29.53 days, to be exact, and is measured from one “New Moon” to the next.
The Phases
Here, we’ll break down each of the 8 phases of the Moon, highlighting the 4 key ones (in bold) as it revolves around the Earth in the Northern Hemisphere. Refer to the corresponding numbered phases in the diagram in this article to follow along.
The Phases of The Moon
- New Moon. When we are in the “New” Moon phase, the Moon is not visible from our perspective because it is positioned between the Sun and Earth. The portion of the Moon that is actually getting sunlight is the back side of the Moon, the half that we cannot see. It’s called the New Moon because it’s the beginning of the lunar cycle. Push the “reset button” and let the 30-day orbit begin!
- Waxing Crescent – After the New Moon, the Moon continues its journey around the Earth, becoming visible as it moves on its path toward becoming a Full Moon. The sunlit portion is increasing. A crescent Moon is easy to identify as it looks like a sliver in the sky. Waxing = growing in illumination.
- First Quarter Moon. This one confuses a lot of people. In this case, the term is used because the Moon is in the first quarter of the 30-day cycle, but it appears half full. The First Quarter and Last Quarter Moons (both called “half moons”) happen when the Moon is at a 90 degree angle with respect to the Earth and Sun. So we are seeing exactly the half of the moon that gets hit by the Sun’s light.
- Waxing Gibbous – Still growing as we head toward full. More than half of the Moon is illuminated by the Sun. Gibbous = more than half. Waxing = growing in illumination.
- Full Moon. The full Moon comes about 15 days (14.8 to be exact) after the New Moon, the mid point of the cycle (half of 30 = 15). The Moon is now in alignment with the Earth and Sun again, just as in the New Moon phase, but this time, the Moon is on the opposite side of Earth, so the entire portion of the moon that is lit by the Sun is facing us. After this phase, visibility starts decreasing.
- Waning Gibbous – Waning = decreasing in illumination as we head toward the darkness of the next New Moon. Gibbous = more than half.
- Last Quarter Moon (sometimes called the Third Quarter Moon). This is when the Moon completes the third quadrant of its phase cycle, about 22.1 days after the New Moon phase. And, as in #3, it looks like a half Moon to us again, except this time, it’s heading toward the New Moon phase (disappearing) instead of growing toward the full Moon phase.
- Waning Crescent – The Moon is a little sliver of a crescent, just as in #2, but the illuminated part is decreasing. Waning = decreasing in illumination. Now, the illuminated crescent is facing the opposite direction as when it was a waxing crescent (see #2).
If you look in the sky and see a crescent or gibbous Moon, you would be able to tell if it is in the waxing or waning phase by the direction it’s curving.
Two terms to memorize:
Waxing = Growing in illumination
Waning = Shrinking in illumination
So there you have it. We’re happy to answer any questions to help you understand this fascinating and complex astronomical occurrence. Just leave them in the comments below.
Check out our Moon Phases Chart so you can see each phase, day by day, for the entire month!
Want to see the whole process in animation using real images of the Moon? Watch this amazing video courtesy of NASA:
If you notice a hole in the upper left-hand corner of your Farmers' Almanac, don't return it to the store! That hole isn't a defect; it's a part of history. Starting with the first edition of the Farmers' Almanac in 1818, readers used to nail holes into the corners to hang it up in their homes, barns, and outhouses (to provide both reading material and toilet paper). In 1919, the Almanac's publishers began pre-drilling holes in the corners to make it even easier for readers to keep all of that invaluable information (and paper) handy.
18 comments
Thank you. Very clear, short and simple explanation. And the video is helpful for kids
what about the yellow moon?
why is this sooo hard like… its so hard to under stand the movement
umm… ok
Hi Reinaldo, When the Moon is full, and at its brightest, it sits directly opposite the Sun in the sky, which means it is below the horizon while the Sun is up. The New Moon rises during the day, but sits too close to the Sun to be seen. It sets at night, which is why the night sky is dark during the New Moon. It’s only as the Moon gets close to its quarter phases that the conditions are ideal for it to be seen during the day. That is, it is bright enough, far enough away from the Sun to be seen, and rises or sets during daylight hours. When all of these conditions come together, and when the sky is clear enough, the Moon becomes visible during the daytime.
According to your diagrams of the moon phases and the earth and suns positions, how do you explain a full moon during the day?
Reinaldo Perez
Check this printable calendars with lunar phases: http://calmoon.com
Calendar based on U.S. Naval Observatory data and actual for Northern Hemisphere (London).
I enjoy these types of posts but I find myself losing hours simply browsing and reading. Keep them coming.
http://www.spasaadelaide.com.au/
Hi Braden Mende – The diagram isn’t completely accurate because the moon doesn’t orbit the Earth in a true circle. It’s more oval in shape. So there aren’t perfect line ups to block the Sun’s rays. The Earth only blocks the Moon receiving sunlight when there is a total eclipse — a straight lineup of Moon, Earth and Sun. Otherwise, it’s not completely lined up and the Moon is receiving light from the Sun. Take a look at a further explanation here: http://farmersalmanac.wpengine.com/astronomy/2015/04/13/eclipses-at-full-and-new-moon/
How can a full moon be possible at #5 if the earth is blocking the sunlight from the moon?
i really like it..i learn something about it.
This si a good article. thank you for explaining. My astrologer did not even explain it.
My husband and I had a farm 38 years. He always farmed by the Almanac. I do my flowering by the Almanac.Thank you. I had a beauty shop and cut hair by the Almanac. Love it.
As a backyard gardener, I am learning gardening by the moon phases (I am noticing it makes a difference in plant health and yield). Thank you Farmers Almanac!
Patricia Cole, it’s only useful for memorization if this is a topic that interests you.
OK, now I know this but not have memorised it, what do I do with this into? How is it helpful to me?
Thank you, Janet Davis!
I live in an area where surface light is a bare minimum. There are no street lights, either. I enjoy the moon phases immensely and have learned a lot from the Farmers Almanac.
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