<p>The Moon’s orbit is slightly tilted (about 5.15°) with respect to the <em>ecliptic</em>, and the direction of this tilt is variable over a period of about 18.61 years. This means its tilt with respect to the <em>equator</em> is variable. But even if it weren’t, when the Moon is near the node (the crossing of its orbit with the equator), its “vertical” movement becomes faster, and it’s slower around 90° from the nodes. This explains why sometimes there is more or less time between two successive moonrises or moonsets, as the declination of the Moon “compensates” for its difference in right ascension which would make its risings and settings (almost) regularly spaced from each other.</p>

CC BY-SA 4.0
2023-06-06T21:01:20.400Z
2023-06-06T21:01:20.400Z
Pierre Paquette
<p>I generated ephemeris for my town (15.10, 17.03) and what caught my attention is for some days in a row, the difference between moonrise is like 15 minutes (diffence between moonset is ~1h at a time):<a href="https://i.sstatic.net/PW3Mq.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/PW3Mq.png" alt="enter image description here" /></a></p>
<p>However a couple days later situation is mirrored for moonset, namely difference between moonset in like ~25min and difference between moonrise is more than hour.</p>
<p>Could someone explain this to me? Thank you!</p>
<p>Link to <a href="https://in-the-sky.org/ephemeris.php?ird=1&amp;irs=1&amp;ima=1&amp;iob=1&amp;objtype=1&amp;objpl=Moon&amp;objtxt=the%20Moon&amp;tz=0&amp;startday=6&amp;startmonth=6&amp;startyear=2023&amp;interval=4&amp;rows=250" rel="nofollow noreferrer">ephemeris</a>.</p>

CC BY-SA 4.0
2023-06-07T01:48:51.493Z
Also see https://astronomy.stackexchange.com/questions/48591/the-moon-rises-at-a-different-time-each-day-but-that-difference-changes-why
JohnHoltz
<the-moon>
Moonrise and moonset roughly at the same hour for few days
3igen3ggy
# Moonrise and moonset roughly at the same hour for few days

(Asked by: username_0 on 2023-06-06)

I generated ephemeris for my town (15.10, 17.03) and what caught my attention is for some days in a row, the difference between moonrise is like 15 minutes (diffence between moonset is ~1h at a time):[![enter image description here](https://i.sstatic.net/PW3Mq.png)](https://i.sstatic.net/PW3Mq.png)

However a couple days later situation is mirrored for moonset, namely difference between moonset in like ~25min and difference between moonrise is more than hour.

Could someone explain this to me? Thank you!

Link to [ephemeris](https://in-the-sky.org/ephemeris.php?ird=1&irs=1&ima=1&iob=1&objtype=1&objpl=Moon&objtxt=the%20Moon&tz=0&startday=6&startmonth=6&startyear=2023&interval=4&rows=250).

**Tags:** the-moon
> **Comments:**
> **username_1**: Also see https://astronomy.stackexchange.com/questions/48591/the-moon-rises-at-a-different-time-each-day-but-that-difference-changes-why  

---

## 1 answers

### Answer by username_2 on 2023-06-06. Score: 2 | Accepted answer

The Moon’s orbit is slightly tilted (about 5.15°) with respect to the *ecliptic*, and the direction of this tilt is variable over a period of about 18.61 years. This means its tilt with respect to the *equator* is variable. But even if it weren’t, when the Moon is near the node (the crossing of its orbit with the equator), its “vertical” movement becomes faster, and it’s slower around 90° from the nodes. This explains why sometimes there is more or less time between two successive moonrises or moonsets, as the declination of the Moon “compensates” for its difference in right ascension which would make its risings and settings (almost) regularly spaced from each other.


---

