The phases of the moon are one of the most famous scenes in the night sky. Every month we see our lonely satellite grow and disappear through a series of shapes, taking it from the inevitable full month all the way to a tiny fraction of the crescent, which briefly disappears completely from view, and then returns to fullness.
What are the phases of the moon?
We say the moon is “new” when light from the moon does not reach the Earth. Over time, we begin to see more and more of this and say the moon is rising. First we see the rising crescent, and then the so-called “first quarter of the moon.” It’s a bit of a confusing name because it actually appears as a dimly lit moon in the night sky. But if you think about it, the Moon can be divided into four quarters: two on the side of the Moon facing us, and then two on the side facing away from the Earth. During the first quarter of the month, sky watchers see the quarter whole The moon is shining.
Next comes the rising gibbos Moon – part of the way between the first quarter and the full moon. It comes from the old Middle English word for “hump” because it is a shape reminiscent of the night sky. After a full moon we say that the moon begins to decline. So the waning gibbous comes first, followed by the last quarter of the month, the waning crescent, and then once again the new moon. It takes 29.5 days to go through this cycle of phases once, according to the Lunar and Planetary Institute.
What is the moon phase today?
|Date||Moon phase||weather (ET)|
|May 8||The first quarter||20:21|
|May 16th||Full moon||12:14|
|May 22nd||Third quarter||14:43 hours|
|May 30th||New Moon||7:30 in the morning|
|June 7th||The first quarter||10:48 in the morning|
|June 14th||Full moon||7:51 in the morning|
|June 20th||Third quarter||23:10|
|June 28th||New Moon||22:52|
As the phases of the moon are caused by the moon’s orbit around the earth, they are completely predictable. In fact, it is possible to determine the dates when we will see these phases for the next 50 million years. Here’s what it will look like tonight:
Why does the Moon have phases?
“The moon is only visible to us because it reflects sunlight,” said Dhara Patel, a space expert at the UK’s National Space Center in Leicester. “Wherever the Moon is in its orbit around the Earth, it is always half illuminated by the sun.” Patel told Live Science. The same goes for the Earth – half of us experience the day, while the other half experience the night.
The same half of the Moon is always also facing the Earth. “The moon revolves around its axis and orbits the earth at the same time – it’s called synchronous rotation,” Patel said. Sometimes the illuminated half of the moon coincides with the half facing the Earth. In that case we see the Full Moon. This happens when the moon is on the opposite side of the Sun from the Earth. The Earth does not normally block sunlight because the Moon’s orbit is slightly tilted. When the Earth blocks the light, we see a lunar eclipse.
When the moon is between the Earth and the Sun, the sunlight fully illuminates the half that is facing away from us and so we do not see the light or the new Moon at all. Again, the tilt of the moon’s orbit usually prevents the moon from blocking our view of the sun. When it happens occasionally, we see a solar eclipse.
When sunlight falls partly on our side and partly on the other, we see intermediate phases such as the crescent, quarter, and crescent, according to Sky and Telescope.
What is the dark side of the moon?
People often call the side of the moon that always points away from us the “dark side of the moon,” perhaps in part because of Pink Floyd’s self-titled album. It may be a common phrase, but, according to Patel, it is not the correct terminology to use. “The moon has no dark side, it has a far side,” Patel said. That far side is very rarely completely dark – during the full moon when our side is fully lit. At any other time, the far side is at least partially illuminated, she said.
What is the lunar or lunar calendar?
“Throughout human history, many different civilizations and cultures have used the moon to dictate their calendars,” Patel said. IN Gregorian calendar, years are divided into months, which comes from the word “months”. The average length of a calendar month is very close to 29.5 days as needed for a cycle of lunar phases.
The date of the Christian holiday of Easter, for example, is calculated using the moon. Easter Sunday falls on the first Sunday after the full moon that occurs on or after Spring equinox. If the full moon falls on a Sunday, then Easter is next Sunday.
The Jewish and Islamic calendars are also based on the moon.
And Chinese, Vietnamese, Hindu and Thai calendars are also still based on the moon. “In some cultures, the full moon is given a special name each month to make it easier to keep track of time and seasons,” Patel said.
- Learn more about the phases of the moon using this amazing interactive website OUR.
- Hear about the moon’s violent birth and how the moon’s phases shaped our lives in this video from National Geographic.
- And for an extremely deep dive, find out everything you ever wanted to know about Earth’s ubiquitous satellite in the book. “The Book of the Moon: A Guide for Our Nearest Neighbor“(Abrams Image, 2019).