7 replies to this topic

[james7ca]

Next week there will be a very good opportunity to image or view the full moon (if you live in the northern part of the western hemisphere). The moon will reach its full phase on Wednesday evening December 11 (or shortly after midnight on the east coast) and at my location on the west coast that will happen at 9:13pm PST when the moon is standing at 54 degrees in altitude. Then, about 2.5 hours later the barely waning moon will pass through my meridian at an altitude of 78 degrees. Everyone further east of the Pacific coast will have an even better opportunity since the time of the full moon will be even closer to the hour when the moon is highest in the sky. The exact time of the full moon will be 5:13UTC on Thursday, which for the east coast will be just after midnight. Those in the eastern time zone will probably have the best view as the full moon will be passing through their local meridian just as it reaches its full phase.

 

For example, in Miami the moon will pass through the local meridian at an altitude of nearly 86 degrees at 12:15AM which is just two minutes after the moon reaches its full phase.

 

It's only in the winter months that the full moon will appear this high in the sky and it's fairly rare for any particular location on the earth to have a completely full moon passing through their local meridian. Yes, it happens somewhere on the earth every month, but not necessarily where you happen to be located. However, it looks like for the next few years the western hemisphere is going to be favored during the month of December (close to the winter solstice when the full moon is highest in the sky).

 

[james7ca]

Below is a list of the dates and times for the full moons that will occur around the winter solstice for the next five years (rounded to the nearest minute or two). For each full moon that occurs in December I've included the elevation/altitude that the moon will appear at for my location near San Diego, CA and the offset in hours from when the moon will be on my local meridian (rounded to the nearest half hour). A negative offset means the moon is full before it reaches my meridian and I'd want this offset to be as close to zero as possible since that would indicate that the moon was at its full phase as it reached my local meridian (thus, being at its highest point in the sky).

 

Ideally, what you want is a time around midnight for the full moon and what you don't want is a time around noon (since the latter would mean the full moon occurs below your horizon). Also, the closer to the winter solstice the better.

 

For those who are in different time zones you can estimate the "goodness" of any particular event by adding the number of hours you are east of the Pacific time zone (or subtract if west). Thus, the eastern time zone correction would be +3 hours and that means next week's full moon will be very close to the meridian for observers in the eastern U.S. (as discussed in my initial post). You can see that for the next three years the east coast is favored and that my location won't have a better event that is this close to the winter solstice until December 15, 2024.

 

This run of good December events for the east coast is somewhat lucky and this cycle should shift year by year and decade by decade. It also means that observers who are on the opposite side of the earth (from the east coast of North America) will be somewhat out of luck for full moon observing over the next few years since for them the actual full moon phase will happen when the moon is below their local horizon (unless you happen to be far enough north that the moon never sets, but in that case the moon will still be pretty low in the sky). Of course, at some time in the future the situation will be reversed and those on the opposite side of the earth will be favored for these events.

 

Dec. 11, 2019 9:14PM PST, 54º 31  59”, -2.5h (east of the meridian, favors those further east).

Jan. 10, 2020 11:22AM PST (below the horizon)

 

Nov. 30, 2020 1:29AM PST

Dec. 29, 2020 7:28PM PST, 31º 50’ 20”, -4.5h

Jan. 28, 2021 11:18AM PST

 

Nov. 19, 2021 12:58AM PST (this will also be a good event for the west coast, altitude 66º 19’ 9”, +1.5h)

Dec. 18, 2021 8:35PM PST, 47º 34’ 7”, -3h

Jan. 17 2022 3:48PM PST

 

Nov. 8 2022 3:02AM PST

Dec. 7 2022 8:09PM PST, 43º 20’ 41”, -3.5h

Jan. 6 2023 3:09PM PST

 

Nov. 27, 2023 1:15AM PST

Dec. 26 2023 4:33PM PST, On Eastern Horizon (-00º 7’ 30”), -7.5h

Jan. 25, 2024 9:55PM PST

 

Nov. 15, 2024 1:30PM PST

Dec. 15, 2024 1:01AM PST, 72º 15’ 44”, +1.5h (past the meridian, favors those further west)

Jan. 13, 2025 2:26PM PST

 

Note, I double checked all of the December events so they should be correct. However, the November and January dates could have typos/errors.

Edited by james7ca, 05 December 2019 - 12:51 AM.

[james7ca]

Here is a simulation from NASA's Scientific Visualization Studio that shows the changes along the waning limb of the full moon over six hours for next week's event. If you look carefully you can see slight changes between the 9PM and midnight simulations, while the six hour change from 9PM until 3AM the next morning is pretty apparent (look at the craters Plutarch -- top of image -- and Balmer -- bottom of image). You can see the progression of the shadows on the floor of those craters. There is also a change in the libration of the moon, which when switching between the simulations is pretty apparent.

 

So, will I be able to notice a difference between the 9:14PM event (when the moon is completely full) and the time that the moon crosses my meridian at 11:49PM? Probably so, but while I think it will be more apparent than indicated by the simulation it will probably not be a dramatic change.

 

That said, the weather forecasts are not that hopeful but things could change over the next week (either to better or worse). So, it's either clear skies next Wednesday or maybe a wait until 2024.

Attached Thumbnails

• 

[Tom Glenn]

James, nice posts.  There is always more than initially meets the eye with the Moon.  You are correct that the exact moment of the Full Moon is not often observed, at least not while the Moon is well positioned for imaging.  Because most people image the Moon either slightly before or after it is full, there is usually a slight terminator present on the eastern or western limb.  But even if you manage to catch the Moon when totally full, most people are unaware that the Full Moon is almost never 100% illuminated.  This is because the Full Moon lies above or below the ecliptic (except during lunar eclipses) and so depending on the libration to the north or south, you almost always get somewhat of a view over one of the poles and can see the terminator.  At extreme librations, the Full Moon is an excellent time to image the polar region that is tipped towards Earth.  Also interesting is that different locations on Earth will have slightly different libration angles, due to parallax, and this can actually be quite significant when attempting to peer over the lunar limb.  Next week's Full Moon actually does not have a particularly strong libration in latitude (only about 2 degrees to the north), and so there won't be much relief to be seen near the north polar region, but there will be some.  In contrast, the south polar region will not have any shadows.  

[james7ca]

Yes, the libration makes a difference and as you noted this week's full moon is pretty much face on to the earth. I looked at both the north and south poles in the simulation and decided there was no reason to post those parts of the simulation since there wasn't a lot to see (very few to no shadows).

 

For those in southern Florida this could be one of the "best" full moons for the next decade or more. 

 

Right now the weather forecast for southern California are kind of mixed, but there is supposed to be clearing starting on Wednesday and maybe even some clear nights on Thursday and Friday. If I had to predict I'd say it will be cloudy here on the night of the full moon (during the event) and then we'll have our first clear nights in several weeks right when the moon is just past full. 

Edited by james7ca, 08 December 2019 - 06:39 AM.

[james7ca]

I was wondering when we might have out next lunar eclipse and so I checked the coming events to see if there was an eclipse that would happen near to the winter solstice (to match the list for the full moons). As it happens, a few of the events that I posted will also be lunar eclipses. So, below is an update showing the lunar eclipses (the times are for the west coast).

 

Perhaps the most interesting for the west coast is the nearly total lunar eclipse (97%) on November 19, 2021. Best seen from Hawaii, but still with the eclipsed moon at about 66º altitude when viewed from near San Diego.

 

The November 8, 2022 total lunar eclipse will be better further west and in Honolulu it will 78º above the horizon at full eclipse.

 

 

Dec. 11, 2019 9:14PM PST, 54º 31’ 59”, -2.5h (East of the meridian, favors those further east).

 

Jan. 10, 2020 11:22AM PST (Below the horizon, but a penumbral lunar eclipse visible from Asia)

 

Nov. 30, 2020 1:29AM PST (Penumbral lunar eclipse visible from Hawaii and most of the continental U.S.)

 

Dec. 29, 2020 7:28PM PST, 31º 50’ 20”, -4.5h

 

Jan. 28, 2021 11:18AM PST

 

Nov. 19, 2021 12:58AM PST, 66º 19’ 9”, +1.5h (This will be a good event for the west coast, also, it's going to be a partial lunar eclipse -- nearly total -- visible from Hawaii and most of the continental U.S.)

 

Dec. 18, 2021 8:35PM PST, 47º 34’ 7”, -3h

 

Jan. 17 2022 3:48PM PST

 

Nov. 8 2022 3:02AM PST (Total lunar eclipse visible from Hawaii and western continental U.S.)

 

Dec. 7 2022 8:09PM PST, 43º 20’ 41”, -3.5h

 

Jan. 6 2023 3:09PM PST

 

Nov. 27, 2023 1:15AM PST

 

Dec. 26 2023 4:33PM PST, -00º 7’ 30” (On horizon), -7.5h

 

Jan. 25, 2024 9:55PM PST

 

Nov. 15, 2024 1:30PM PST

 

Dec. 15, 2024 1:01AM PST, 72º 15’ 44”, +1.5h (Past the meridian, favors those further west)

 

Jan. 13, 2025 2:26PM PST

 

Beyond the above, here are the next lunar eclipses that would be visible from the continental U.S. during the winter months (not many going out for the next 15 years, Asia, Europe and Africa seem favored):

 

January 12, 2028 (Partial lunar eclipse visible from continental U.S.)

January 21, 2038 (Penumbral lunar eclipse visible from eastern U.S.)

Edited by james7ca, 09 December 2019 - 03:27 AM.

[james7ca]

The weather in San Diego looks somewhat questionable for tomorrow's full moon event. It probably won't be totally overcast, but it could range from totally clear to partly cloudy (35%) between 9PM and midnight.

 

However, the Canadian Meteorological Centre is predicting almost complete overcast for the entire state of Florida. That's unfortunate since for Florida and most of the eastern U.S. this will be a once in a decade (or more) type event.

 

Here is a link to the cloud forecast for the western U.S. (9PM PST Wednesday evening, forecast is for mixed conditions):

 

  https://weather.gc.c...STRO_nt_041.png

 

Here is a link to the cloud forecast for the eastern U.S. (Midnight, Thursday morning, forecast for South Carolina and points north looks good):

 

  https://weather.gc.c...STRO_nt_041.png

 

Note, I don't know if the above links are absolute time based or relative time based, meaning that later tonight or tomorrow they may no longer show the forecast for December 12, 5:00 UTC. However, the UTC time is listed on the map and in any case here is the link to the full set of cloud forecast (where you can pick your own date/time):

 

  https://weather.gc.c...clds_vis_e.html

Edited by james7ca, 11 December 2019 - 02:28 AM.

[james7ca]

Looks like no joy for us in southern California (clouds), but the central Atlantic coast and some points just west of the Appalachians should have clear skies tonight for the high-rising full moon. But, I think it is going to be cold out there (around midnight eastern time).

 

Since there is no rain in the forecast (just clouds) I may go for broke and get out my EdgeHD. Maybe I'll get a few cloud-free minutes around 9PM when I can try to image.

Edited by james7ca, 11 December 2019 - 09:34 PM.