Lunar X
& V Times for 2018
The Lunar X and V are optical effects which are visible on
the lunar surface for about 3 hours, once a month. They are caused by sunlight
illuminating the edge of craters. The X is caused by light illuminating the
rims of craters Blanchinus, La Caille and Purback. The V is caused by light
illuminating crater Ukert along with several smaller craters.
The X and V are usually visible a few hours before First
Quarter phase, however, due to libration, the exact time of the X and V being
visible is different from month to month.
I usually publish the times of the Lunar X and V on my monthly sky notes
article, but also find it useful to have this information to hand for all
months of the year. As I did last year, I used the NASA Scientific
Visualisation Studio Moon Phase and Libration tool, but the 2018 version. I
used this to scroll through each month close to First Quarter Phase, hour by
hour, until I could record the times of the X and V being visible. The times I recorded are listed below. These times are approximate because I just
scrolled through hour by hour. If you
want to have a go a looking for a more accurate time yourself, then visit: https://svs.gsfc.nasa.gov/4604
Please note that although the X and V are visible every
month, they may occur before the Moon has risen or after it has set from your
location, so you will not see them every month from any one location. Please
also note that the times given are in 24 clock and are in UT (the same as GMT)
so you will need to correct for time zones and daylight time savings changes.
Lunar X and V Times for 2018
24th January
|
04:00 UT
|
22nd February
|
17:00 UT (visible from UK)
|
24th March
|
06:00 UT
|
22nd April
|
18:00 UT (19:00 BST - visible from UK)
|
22nd May
|
06:00 UT
|
20th June
|
18:00 UT (19:00 BST - visible from UK)
|
20th July
|
05:00 UT
|
18th August
|
17:00 UT (18:00 BST - visible from UK)
|
17th September
|
05:00 UT
|
16th October
|
18:00 UT
|
15th November
|
08:00 UT
|
14th December
|
22:00 UT (visible from UK)
|
Mary McIntyre
www.marymcintyreastronomy.co.uk
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www.marymcintyreastronomy.co.uk
Follow me on social media:
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The long ray that crosses the Mare Crisium and beyond is interesting me in the shot on the right
ReplyDeleteThe ray that crosses the Sea of Serenity is the Vessel Ray. Not sure I can see anything on Crisium
ReplyDeleteHi, As I had the opportunity to see the last Lunar-X with my kids (fascinating!!!), I wonder if there is a forcast for the year 2019.
ReplyDeleteAnother question: how did you get theses dates and time?
Thanks!!
Hi Frederic,
DeleteSo sorry for not replying sooner!
As I explained in the text, I used the NASA dial-a-moon Moonphase and Libration tool to figure out exactly when the X and V appear. I do this by starting a day before first quarter phase then scrolling through hour by hour until I see the X appear. The 2019 dial-a-moon tool is not yet available for me to check the times, but there is a post on Cloudy Nights forum listing the times for next year. You can find that article here: https://www.cloudynights.com/topic/630098-lunar-x-start-times-2019/