Starship Asterisk*

A Super Moon's Halo

Explanation: A Full Perigee Moon rose as the Sun set last Sunday. At its closest to Earth it was, by just a bit, the year's brightest and largest Full Moon also known as a Super Moon. Seen from Punta Piedras, Argentina and the mouth of the Rio de La Plata, near Buenos Aires, the Super Moon's light created this magnificent circular lunar halo. Still, the size of a lunar halo is determined by the geometry of six sided water ice crystals in planet Earth's high, thin clouds. The crystals deflect the rays of moonlight more strongly through a minimum angle of 22 degrees. So this halo has an inner radius of 22 degrees, just like the halos of the less-than-super moons. Even more common than a Super Moon, beautiful 22 degree halos can be spotted at any time of year.

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I have a question about the reflection of the moonlight in the water. In the photo, the moon reflects in the water in the foreground. Then the reflection stops in the distance. And then, near the horizon line, there is a second white reflection in the water. Why is that ? Why does it stops (does it has to do with earth curvature) ? why does it starts again near the horizon (I have no clue) ? Thanks for your answer.

francis wrote:I have a question about the reflection of the moonlight in the water. In the photo, the moon reflects in the water in the foreground. Then the reflection stops in the distance. And then, near the horizon line, there is a second white reflection in the water. Why is that ? Why does it stops (does it has to do with earth curvature) ? why does it starts again near the horizon (I have no clue) ? Thanks for your answer.

I am thinking it has to do with the Halo actually reaching below the horizon, but just at that point there is still allot of light from it. The other could be the photography...probably a time laps....so it gathered allot of light...and there was enough gathered to show that spot better. There seems to be a "ray" from the moonshine also that reaches down to that point.....also....if you look to the left, under the reddish clouds...you can see another reflection that is brighter than the surrounding area...but it seems to be atmosphere, where the other appears to be ocean.
My best guess, Captain... other than that, sensors are incapable of further data, at this time....

:---[===] *

francis wrote:
I have a question about the reflection of the moonlight in the water. In the photo, the moon reflects in the water in the foreground. Then the reflection stops in the distance. And then, near the horizon line, there is a second white reflection in the water. Why is that ? Why does it stops (does it has to do with earth curvature) ? why does it starts again near the horizon (I have no clue) ? Thanks for your answer.

The water near shore is extremely calm thereby creating almost a mirror reflection.

Far offshore the waves pickup again, perhaps even whitecaps, and one observes a non-specular reflection.

Beautiful capture Luis!
Nice of the Moon to dress up for the occasion!

APOD Robot wrote:The crystals deflect the rays of moonlight more strongly through a minimum angle of 22 degrees.

Any explanation for this?

Sinan İpek wrote:

APOD Robot wrote:The crystals deflect the rays of moonlight more strongly through a minimum angle of 22 degrees.

Any explanation for this?

Yes, and clicking on the link provide supplies it.

On Christmas Eve, 2012, I shot this photo of a lunar halo using a fisheye lens on my Nikon ...http://smccabe.net/Christmas_Moon.jpg. It's difficult to get everything exposed properly since the Moon is so bright compared to the other items in the scene. Good job on the APOD picture!

Thank you for the messages!

I'm curious if this is close to the brightest a Lunar Halo can ever be, because of the full Moon and perigee times.
The colors of the halo were easy to see with the naked eye and that's not common for lunar halos.
It lasted almost all night.
The sky inside the halo is darker than the sky outisde I think that can be like the Alexander Band seen in rainbows. Halos and rainbows have some similarities, for example both are polarized.

Later in the same night I also photographed a rare infralateral halo or part of a 46 degrees halo. It can be seen here: http://www.luisargerich.com/superhalo20 ... #h69ea2cfe

Boomer12k wrote:

francis wrote:I have a question about the reflection of the moonlight in the water. In the photo, the moon reflects in the water in the foreground. Then the reflection stops in the distance. And then, near the horizon line, there is a second white reflection in the water. Why is that ? Why does it stops (does it has to do with earth curvature) ? why does it starts again near the horizon (I have no clue) ? Thanks for your answer.

I am thinking it has to do with the Halo actually reaching below the horizon, but just at that point there is still allot of light from it. The other could be the photography...probably a time laps....so it gathered allot of light...and there was enough gathered to show that spot better. There seems to be a "ray" from the moonshine also that reaches down to that point.....also....if you look to the left, under the reddish clouds...you can see another reflection that is brighter than the surrounding area...but it seems to be atmosphere, where the other appears to be ocean.
My best guess, Captain... other than that, sensors are incapable of further data, at this time....

:---[===] *

Hi, thanks for the explanation.
In case it helps the photo is a single shot and the light from the left comes from the city of Montevideo, Uruguay's capital about 95km across the river.

Very nice photo - congrats Luis Argerich for being picked for today's APOD!

We had thick clouds, and missed seeing the "super moon" at our location.

Thank you all for the explanations and a beautiful picture.

Wonderful picture: thanks for sharing!