Timeline for How does the Moon move in the "night" sky as seen from the poles?
Current License: CC BY-SA 4.0
15 events
| when toggle format | what | by | license | comment | |
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| Apr 2, 2019 at 0:58 | comment | added | uhoh | ever-so-slightly related, more about how the Moon moves: How did Cassini measure the “Cassini state” of the Moon? What measurements were made and what did the data look like? | |
| Jan 16, 2019 at 6:33 | comment | added | uhoh | I've linked to this here | |
| Sep 29, 2018 at 12:13 | vote | accept | uhoh | ||
| Sep 25, 2018 at 2:46 | comment | added | uhoh | @PM2Ring indeed again, ever-so-slightly analogous to a stopped clock being right twice a day, the Moon's nodes will line up with the Earth-Sun line twice a year. Thanks! | |
| Sep 25, 2018 at 2:42 | comment | added | PM 2Ring | @uhoh We could still have eclipses, but they'd be much more rare, since they'd only occur close to the equinoxes. | |
| Sep 25, 2018 at 2:33 | comment | added | uhoh | @PM2Ring "yes indeed" to each of your points. Of course if the Moon where near the Earth's equatorial plane we would not have eclipses, so I was in a constant state of ambiguity and conflict, as I am in all aspects of life, universe, everything... | |
| Sep 25, 2018 at 2:23 | comment | added | PM 2Ring | @uhoh The term "ecliptic" should've been a clue. ;) But anyway, our Moon is a bit odd, since it's so big relative to the Earth. In some ways it's more like a planet that shares our orbit than a moon, so it's not surprising that its orbital plane is close to the ecliptic (but precesses rather quickly due to the complex combination of influences from the Earth and the Sun). Most other moons in the solar system orbit in their primary's equatorial plane, that might not apply to the extremely distant moons. | |
| Sep 24, 2018 at 16:05 | comment | added | uhoh | @RoryAlsop very nice answer; I learned a lot today, thanks! | |
| Sep 24, 2018 at 15:54 | comment | added | uhoh | @SteveLinton oh my goodness, I don't know where the Moon is! I'd assumed it would have found it's way close to the Earth's equatorial plane since the Earth's bulge and J2 are at play, but yes, at 400,000 km the quadrupole moment's $1/r^3$ potential drops off so fast compared to the monopole's $1/r$ that it has little effect, and the solar system's perturbations take over. Ha! my Moon has just moved to where everyone else's has been all along. Thanks! | |
| Sep 24, 2018 at 15:46 | comment | added | Steve Linton | @uhoh There are three planes of interest: the Earth's equator, the Moons orbit and the ecliptic. What makes the Moon (and Sun) intermittently visible from the poles is mostly the 23 degreed between the Ecliptic and the Equator. The 5 degrees between the ecliptic and the Moons orbit should show up as a variation in that basic pattern | |
| Sep 24, 2018 at 15:25 | comment | added | uhoh | @SteveLinton If the Moon's orbit stayed in the Earth's equatorial plane, then wouldn't it always be invisible from either pole? Isn't the Moon's orbit inclination wrt the ecliptic (about 5 degrees) the only thing that allows it to become visible from the poles, ever? (except of course for a small bit of atmospheric refraction) | |
| Sep 24, 2018 at 15:13 | comment | added | Steve Linton | @uhoh At full moon the moon is opposite the sun so visible in winter not in summer. At new moon it is near the sun, so visible in summer (in principle) not in winter. There will be a secondary effect caused by the moon's orbit being inclined 5 degrees to the plane of the ecliptic, which may well change as you describe, but that's dominated by the fact that Earth's equator is inclined 23 degrees | |
| Sep 24, 2018 at 15:09 | history | edited | Rory Alsop | CC BY-SA 4.0 |
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| Sep 24, 2018 at 14:24 | comment | added | uhoh | Is that the Northern hemisphere's winter, or Southern's winter, or both? Or does it swap back and forth with an 18.6 year period? en.wikipedia.org/wiki/Lunar_node | |
| Sep 24, 2018 at 14:19 | history | answered | Rory Alsop | CC BY-SA 4.0 |