# What's the difference between eclipses and a new moon? **URL:** \ **Category:** Factual Questions\ **Created:** [December 11, 2011, 3:13pm UTC](https://boards.straightdope.com/t/whats-the-difference-between-eclipses-and-a-new-moon/605826 "2011-12-11T15:13:59Z")\ **Posts on this page:** 7\ **Page:** 2
**Author:** ![AaronX](https://avatars.discourse-cdn.com/v4/letter/a/7bcc69/32.png) [@AaronX](https://boards.straightdope.com/u/AaronX)\ **Post date:** [September 12, 2012, 1:41pm UTC](https://boards.straightdope.com/t/whats-the-difference-between-eclipses-and-a-new-moon/605826/21 "2012-09-12T13:41:00Z")
Some more moon questions, if I may. Don’t think they’ve been answered before. How do moonrise and moonset times vary? Does the moon always rise around sunset and set around sunrise? What I’m wondering is: is it possible to have moonrise at say, 10 am and moonset at 4 pm so that we don’t see the moon that night? Since the moon’s orbit and Earth’s rotation aren’t in sync, sounds like it could be possible. > [@DHMO](#): > > The normal to [the plane of the Moon’s orbit](http://en.wikipedia.org/wiki/Moon)is not currently “in the same direction” as the Earth’s axis of rotation, but, like the Earth’s axis “[precesses](http://en.wikipedia.org/wiki/Precession),” so does the Moon’s orbit, due to perturbations of the Sun and Earth. At some time in the past, and again at some time in the future, the two will likely point in more or less the same direction. How much is the difference and wobble between the Earth’s and moon’s rotation? Does the moon’s path across the sky vary a lot, say, like the Sun’s? Is the period a year (not likely), a lunar cycle, or something else since it depends on the rotation of both? If I’m looking for the Moon at a certain time, what software is best to use to find its position? ---
**Author:** ![John\_Mace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_mace/32/185_2.png) [@John\_Mace](https://boards.straightdope.com/u/John_Mace)\ **Post date:** [September 12, 2012, 1:49pm UTC](https://boards.straightdope.com/t/whats-the-difference-between-eclipses-and-a-new-moon/605826/22 "2012-09-12T13:49:22Z")
Don’t discussions about the different installments of the _Twilight_ series belong in Cafe Society? . 😃 ---
**Author:** ![John\_DiFool](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_difool/32/19543_2.png) [@John\_DiFool](https://boards.straightdope.com/u/John_DiFool)\ **Post date:** [September 12, 2012, 4:19pm UTC](https://boards.straightdope.com/t/whats-the-difference-between-eclipses-and-a-new-moon/605826/23 "2012-09-12T16:19:05Z")
Given the 5 degree difference between the moon’s orbit and the Earth’s (+/- 5 degrees north or south), and also given the fact that the moon is about half-a-degree in size (as is the sun), then I’d predict that we would see at least a short-duration partial solar eclipse somewhere on the Earth once every 6-8 lunations or so, which, checking Wikipedia’s eclipse schedules, seems to be about right. The moon just has to overlap the sun’s disc going north or south to qualify as an eclipse, so there’s a maximum of one and a half degrees worth of leeway for the moon to intersect the sun. 1.5 out of 10 is about 1 out of 7; however any given spot on the Earth won’t be seeing these eclipses 1 out of 7 times, because typically the penumbral shadow of the moon (which generates the partials) will only follow a fairly narrow path across the surface of the Earth. Feel free to clarify or render more precisely my estimates. ---
**Author:** ![naita](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/naita/32/5862_2.png) [@naita](https://boards.straightdope.com/u/naita)\ **Post date:** [September 12, 2012, 5:50pm UTC](https://boards.straightdope.com/t/whats-the-difference-between-eclipses-and-a-new-moon/605826/24 "2012-09-12T17:50:21Z")
> [@AaronX](#): > > Some more moon questions, if I may. Don’t think they’ve been answered before. > > How do moonrise and moonset times vary? Does the moon always rise around sunset and set around sunrise? A completely full moon will be at its highest at 12 midnight. A completely new moon will be at its highest at 12 noon. So no, the moon doesn’t always rise around sunset. ---
**Author:** ![Malacandra](https://avatars.discourse-cdn.com/v4/letter/m/45deac/32.png) [@Malacandra](https://boards.straightdope.com/u/Malacandra)\ **Post date:** [September 12, 2012, 5:55pm UTC](https://boards.straightdope.com/t/whats-the-difference-between-eclipses-and-a-new-moon/605826/25 "2012-09-12T17:55:35Z")
> [@naita](#): > > A completely full moon will be at its highest at 12 midnight. A completely new moon will be at its highest at 12 noon. So no, the moon doesn’t always rise around sunset. Elaborating: Only when the moon is full is it opposite the Sun in the sky, when you’d expect one’s rising to coincide with the other’s setting. At new, they rise and set together. Any other time, they’re some interval apart, and the interval can be anything greater than zero and less than twelve hours. ---
**Author:** ![CurtC](https://avatars.discourse-cdn.com/v4/letter/c/ce73a5/32.png) [@CurtC](https://boards.straightdope.com/u/CurtC)\ **Post date:** [September 12, 2012, 6:35pm UTC](https://boards.straightdope.com/t/whats-the-difference-between-eclipses-and-a-new-moon/605826/26 "2012-09-12T18:35:56Z")
I’m sometimes amazed at the things I think everyone knows, but I guess some people just don’t pay attention to. Just last Friday, my wife saw the full moon rising about 8:30, and said how it would be really pretty when we were to be boating on the lake the next night. I pointed out that it would be fairly late for that to be, because 1) the moon wouldn’t be rising the next night until close to 9:30, and 2) you’d need to wait a couple of more hours for it to be sort of overhead and lighting things up. She questioned the bit about rising the next night about an hour later - she had just never noticed that the moon rises later every day. And she’s 51 years old! And married to _me_! ---
**Author:** ![CookingWithGas](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cookingwithgas/32/485_2.png) [@CookingWithGas](https://boards.straightdope.com/u/CookingWithGas)\ **Post date:** [September 12, 2012, 6:48pm UTC](https://boards.straightdope.com/t/whats-the-difference-between-eclipses-and-a-new-moon/605826/27 "2012-09-12T18:48:56Z")
> [@brocks](#): > > Nope, not with the naked eye. The Muslim calendar is based on months that begin when the new moon is first seen, and they look for it VERY carefully. Nobody credible has even claimed to have seen it within 12 hours of the actual, bang-on new moon, and claims of less than 15 hours are treated with extreme skepticism. Depending on the alignment, it may take a full day. > > [FREQUENTLY ASKED QUESTIONS ABOUT MOON-SIGHTING](http://moonsighting.com/faq_ms.html) From your link: > [@](#): > > This moment is called “New Moon Birth” or conjunction. At this moment the sunlight falling on the moon cannot come to the earth. In other words new moon is “No Moon”. No one can see this “New Moon” even by most powerful telescopes. So what does your phrase mean “when the new moon is first seen”? [Previous page](https://boards.straightdope.com/t/whats-the-difference-between-eclipses-and-a-new-moon/605826.md?page=1)