<p>No, because we measure &quot;months&quot; (properly Synodic month) and time in general relative to the sun.  So &quot;six months&quot; means &quot;from new moon to new moon six times&quot;.  It doesn't mean six orbits of the moon relative to the stars. (the sidereal month)</p>
<p>Of course if you define &quot;month&quot; to be sidereal month, relative to the stars, then as it is two-and-a-bit days shorter than the synodic month, then yes, it's about 5.5 sidereal months between eclipses in one eclipse season.</p>

CC BY-SA 4.0
2024-10-24T18:48:40.350Z
2024-10-24T18:48:40.350Z
James K
<p>I researched this, and am not satisfied with what I found, so I am asking here.</p>
<p>Here's what NASA says  <a href="https://eclipse.gsfc.nasa.gov/SEsaros/SEperiodicity.html#:%7E:text=The%20time%20interval%20between%20any,to%203000%20CE%20%5B2%5D" rel="nofollow noreferrer">https://eclipse.gsfc.nasa.gov/SEsaros/SEperiodicity.html#:~:text=The%20time%20interval%20between%20any,to%203000%20CE%20%5B2%5D</a>).</p>
<p>According to NASA the periodicity of solar eclipses is 1, 5, or 6 synodic months, but a simple diagram invalidates that.  Draw a large circle representing the earth's orbit around the sun plotted at its center, and plot two points on its circumference about 180° apart representing the earth's position in orbit 6 months apart.  With those two points as center draw two little circles representing the moon's orbit around earth.  Now suppose a solar eclipse happens for one of the little circles, so plot a point for the moon's position in orbit.  The order of the plotted points must be sun-moon-earth in straight line . Now for the other little circle 6 <em>synodic</em> months later, the order of plotted points will be moon-earth-sun in straight line, AND NO SOLAR ECLIPSE WILL OCCUR.  You have to wait half a synodic month for the order of the plotted points to be sun-moon-earth straight line, and you will have two consecutive solar eclipses.  Therefore the periodicity of solar eclipses is 1, 5.5, and 6.5 synodic months.</p>
<p>I wrote a formula for the geocentric lunar latitude in order to communicate this observation to others.  The formula can be found here:</p>
<p><a href="https://stargazerslounge.com/topic/426317-geocentric-lunar-latitude/" rel="nofollow noreferrer">https://stargazerslounge.com/topic/426317-geocentric-lunar-latitude/</a></p>
<p>So am I right, is it 6.5 not 6 months?</p>

CC BY-SA 4.0
2024-10-24T13:30:46.517Z
How could that work? Solar eclipses occur at the New Moon. New Moons are a whole number of synodic months apart. Of course, the exact length of a synodic month varies a little from month to much, but not by that much!
PM 2Ring
CC BY-SA 4.0
2024-10-24T14:28:01.593Z
@PM2Ring, you're right.  The geocentric lunar latitude is zero twice a month, one represents a possible solar eclipse, the other a possible lunar eclipse.  Now I see my mistake.  Thanks.
lee pappas
CC BY-SA 4.0
2024-10-24T20:25:49.590Z
Wouldn't it be easier to just graph the time differences in the Five Millennium Catalog of Solar Eclipses (linked to from your first link)?
Greg Miller
CC BY-SA 4.0
2024-10-26T02:38:38.327Z
@GregMiller, what is the x axis I presume the y axis is the time difference between two consecutive solar eclipses
lee pappas
CC BY-SA 4.0
2024-10-27T15:04:48.903Z
@leepappas Just a counter incremented for each eclipse would do.  But there are lots of ways to visualize it, like a histogram would show you the most common interval.
Greg Miller
<solar-eclipse>
What is the time interval between two consecutive solar eclipses?
lee pappas
# What is the time interval between two consecutive solar eclipses?

(Asked by: username_0 on 2024-10-24)

I researched this, and am not satisfied with what I found, so I am asking here.

Here's what NASA says [https://eclipse.gsfc.nasa.gov/SEsaros/SEperiodicity.html#:~:text=The%20time%20interval%20between%20any,to%203000%20CE%20%5B2%5D](https://eclipse.gsfc.nasa.gov/SEsaros/SEperiodicity.html#:%7E:text=The%20time%20interval%20between%20any,to%203000%20CE%20%5B2%5D)).

According to NASA the periodicity of solar eclipses is 1, 5, or 6 synodic months, but a simple diagram invalidates that. Draw a large circle representing the earth's orbit around the sun plotted at its center, and plot two points on its circumference about 180° apart representing the earth's position in orbit 6 months apart. With those two points as center draw two little circles representing the moon's orbit around earth. Now suppose a solar eclipse happens for one of the little circles, so plot a point for the moon's position in orbit. The order of the plotted points must be sun-moon-earth in straight line . Now for the other little circle 6 *synodic* months later, the order of plotted points will be moon-earth-sun in straight line, AND NO SOLAR ECLIPSE WILL OCCUR. You have to wait half a synodic month for the order of the plotted points to be sun-moon-earth straight line, and you will have two consecutive solar eclipses. Therefore the periodicity of solar eclipses is 1, 5.5, and 6.5 synodic months.

I wrote a formula for the geocentric lunar latitude in order to communicate this observation to others. The formula can be found here:

<https://stargazerslounge.com/topic/426317-geocentric-lunar-latitude/>

So am I right, is it 6.5 not 6 months?

**Tags:** solar-eclipse
> **Comments:**
> **username_1**: How could that work? Solar eclipses occur at the New Moon. New Moons are a whole number of synodic months apart. Of course, the exact length of a synodic month varies a little from month to much, but not by that much!  
> **username_0**: @PM2Ring, you're right.  The geocentric lunar latitude is zero twice a month, one represents a possible solar eclipse, the other a possible lunar eclipse.  Now I see my mistake.  Thanks.  
> **username_2**: Wouldn't it be easier to just graph the time differences in the Five Millennium Catalog of Solar Eclipses (linked to from your first link)?  
> **username_0**: @GregMiller, what is the x axis I presume the y axis is the time difference between two consecutive solar eclipses  
> **username_2**: @leepappas Just a counter incremented for each eclipse would do.  But there are lots of ways to visualize it, like a histogram would show you the most common interval.  

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## 1 answers

### Answer by username_3 on 2024-10-24. Score: 4 | Accepted answer

No, because we measure "months" (properly Synodic month) and time in general relative to the sun. So "six months" means "from new moon to new moon six times". It doesn't mean six orbits of the moon relative to the stars. (the sidereal month)

Of course if you define "month" to be sidereal month, relative to the stars, then as it is two-and-a-bit days shorter than the synodic month, then yes, it's about 5.5 sidereal months between eclipses in one eclipse season.


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