<p>The concept of a month derived from the amount of time it takes for the moon to cycle from new moon to new moon (which is roughly 29.5 days). The modern month has experienced changes from this original concept due to trying to fit a standard number of months within a solar year.</p>

<p>If you divide the lunar month into quarters, each quarter is approximately 7 days long. This is believed to be the origin of the seven-day week.</p>

CC BY-SA 3.0
2015-06-30T02:09:34.123Z
That's likely, but not certain. https://en.wikipedia.org/wiki/Week#History
Keith Thompson
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2015-06-30T13:16:29.923Z
@KeithThompson I added in some uncertainty.
called2voyage
CC BY-SA 3.0
2015-06-29T20:35:39.120Z
2015-06-30T13:16:17.757Z
2015-06-30T13:16:17.757Z
called2voyage
<p>I'm pretty sure that weeks are seven days long because in ancient times people worshipped the sun, moon and the five then-known planets.  The days are even named after these in various languages...</p>

CC BY-SA 3.0
2015-06-30T13:17:47.967Z
Andy, the Wikipedia article Keith Thompson linked says there is no evidence that the connection between the seven days of the week and the seven classical planets goes back to the original Babylonian establishment of the seven-day week.
called2voyage
CC BY-SA 3.0
2015-06-30T13:59:39.533Z
You're right, my understanding of it has always been that originally they used weeks of seven days, plus a longer week to make up the missing day or two.  I was trying to pin down the significance (if names are "significant") of the slightly more modern week though.  Hope that's OK :)
Andy
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2015-06-30T14:00:42.947Z
Sure, I suppose it is on topic since it relates to the planets.
called2voyage
CC BY-SA 3.0
2015-06-30T10:21:48.947Z
2015-06-30T10:21:48.947Z
Andy
<p>I know that a <strong>day</strong> represent the time for the earth to make a full rotation around its own axis and a <strong>year</strong> is the time for the earth to make a full rotation around the sun.</p>

<p>But <strong>does a week represent something?</strong> And a month?</p>

<p>Thank you.</p>

<p>ps: Not sure what tags I need to use, feel free to add/remove them</p>

CC BY-SA 3.0
2015-06-30T02:57:15.507Z
I've made some research but i haven't found this post. Thanks
TroyAndAbed
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2015-06-30T13:19:33.947Z
The duplicate post has some better information in its answer related to the significance of the quarters (they line up roughly with the phases of the lunar cycle).
called2voyage
<earth><fundamental-astronomy>
Does a week represent something in astronomy?
TroyAndAbed
# Does a week represent something in astronomy?

(Asked by: username_0 on 2015-06-29)

I know that a **day** represent the time for the earth to make a full rotation around its own axis and a **year** is the time for the earth to make a full rotation around the sun.

But **does a week represent something?** And a month?

Thank you.

ps: Not sure what tags I need to use, feel free to add/remove them

**Tags:** earth, fundamental-astronomy
> **Comments:**
> **username_0**: I've made some research but i haven't found this post. Thanks  
> **username_1**: The duplicate post has some better information in its answer related to the significance of the quarters (they line up roughly with the phases of the lunar cycle).  

---

## 2 answers

### Answer by username_1 on 2015-06-29. Score: 5 | Accepted answer

The concept of a month derived from the amount of time it takes for the moon to cycle from new moon to new moon (which is roughly 29.5 days). The modern month has experienced changes from this original concept due to trying to fit a standard number of months within a solar year.

If you divide the lunar month into quarters, each quarter is approximately 7 days long. This is believed to be the origin of the seven-day week.

> **Comments:**
> **username_2**: That's likely, but not certain. https://en.wikipedia.org/wiki/Week#History  
> **username_1**: @KeithThompson I added in some uncertainty.  

---

### Answer by username_3 on 2015-06-30. Score: 0

I'm pretty sure that weeks are seven days long because in ancient times people worshipped the sun, moon and the five then-known planets. The days are even named after these in various languages...

> **Comments:**
> **username_1**: Andy, the Wikipedia article Keith Thompson linked says there is no evidence that the connection between the seven days of the week and the seven classical planets goes back to the original Babylonian establishment of the seven-day week.  
> **username_3**: You're right, my understanding of it has always been that originally they used weeks of seven days, plus a longer week to make up the missing day or two.  I was trying to pin down the significance (if names are "significant") of the slightly more modern week though.  Hope that's OK :)  
> **username_1**: Sure, I suppose it is on topic since it relates to the planets.  

---

