<p>If the synodic lunar cycle or period is related to the tropical lunar cycle by the alignment of a full moon at a specific longitude, what is the equivalent synodic cycle for the draconic or nodal crossing of the ecliptic plane called? I would think this is important for eclipse cycles. I tried searching for a &quot;synodic draconic&quot; combination but nothing came up. This is obviously not a homework problem ;)</p>

CC BY-SA 4.0
2024-12-26T23:21:22.647Z
Its not clear what you are asking for.  There is the period from one full moon to the next (synodic month)  or for the moon to pass the same location in the sky (sidereal month if measured relative to stars or tropical if measured relative to point of Aries) An there is the time from one node to the next (draconian month) The synodic period isn't related to the tropical period, they measure different things. The draconian month measures a third thing.  It is the draconian month that is important for eclipse cycles (along with the synodic)
James K
CC BY-SA 4.0
2024-12-26T23:29:04.347Z
There are quite a few cycles specific to eclipses, the Saros Cycle being the most popular.  I have heard the moon being near one of the nodes frequently referred to as "elcipse season", but haven't seen any name given to a cycle of them.
Greg Miller
CC BY-SA 4.0
2024-12-28T19:59:33.363Z
*"The synodic period isn't related to the tropical period"*   The relationship is 1/T_synodic = 1/T_tropical - 1/T_annual.  I think my question is not answerable because the draconic cycle already only interacts with the ecliptic plane so the annual aspect is irrelevant. Thanks for the input.
Paul Pukite
<the-moon><ecliptic><synodic-period>
Equivalent of the lunar synodic period for the draconic cycle
Paul Pukite
# Equivalent of the lunar synodic period for the draconic cycle

(Asked by: username_0 on 2024-12-26)

If the synodic lunar cycle or period is related to the tropical lunar cycle by the alignment of a full moon at a specific longitude, what is the equivalent synodic cycle for the draconic or nodal crossing of the ecliptic plane called? I would think this is important for eclipse cycles. I tried searching for a "synodic draconic" combination but nothing came up. This is obviously not a homework problem ;)

**Tags:** the-moon, ecliptic, synodic-period
> **Comments:**
> **username_1**: Its not clear what you are asking for.  There is the period from one full moon to the next (synodic month)  or for the moon to pass the same location in the sky (sidereal month if measured relative to stars or tropical if measured relative to point of Aries) An there is the time from one node to the next (draconian month) The synodic period isn't related to the tropical period, they measure different things. The draconian month measures a third thing.  It is the draconian month that is important for eclipse cycles (along with the synodic)  
> **username_2**: There are quite a few cycles specific to eclipses, the Saros Cycle being the most popular.  I have heard the moon being near one of the nodes frequently referred to as "elcipse season", but haven't seen any name given to a cycle of them.  
> **username_0**: *"The synodic period isn't related to the tropical period"*   The relationship is 1/T_synodic = 1/T_tropical - 1/T_annual.  I think my question is not answerable because the draconic cycle already only interacts with the ecliptic plane so the annual aspect is irrelevant. Thanks for the input.  

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## 0 answers

