Monday, April 02, 2012
Solar and Lunar Halos
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On the way back from boogie boarding with the boys, I notices a 22 degree solar halo. These are rare in Adelaide, and I was able to show the exchange students. We took the exchange students out to Schnitzels at the Largs Peir pub. On the way back, the thin high cloud that had made the solar halo had hung around, making a Lunar halo as well (image isn't as good as I had no tripod).
Sunday, August 14, 2011
Sun Halo
High ice crystals in the clouds make a colourful halo around the sun (click to embiggen)
Friday, February 25, 2011
A Halo in the Sky
Walking home I caught this 22° halo around the Sun. These occur when sunlight is refracted through hexagonal ice crystal high in the atmosphere. It is one of the commonest sky phenomena there is. I've seen quite a few around the Moon, but this is only the second I've seen around the Sun.There is also a tangent arc, which is my first one of them. Just shows what happens when you keep your eyes open.
Here is a few images I've made of halos around the Moon.
Labels: Halo, rainbows, sky phenomena
Saturday, January 15, 2011
Sorry to Dissapoint the Nibiru Folks, It's Just a Sun Halo
This image is doing the rounds of a news aggregator site at the moment.The text breathlessly exclaims:Is this "halo" magnetic, does it interfere with biological processes on Earth? Could it be the source of a magnetic disruption which destroyed or altered the navigational abilities of the now dead birds, bats, and fish?
Sorry guys, but this is a plain old 22° halo. It occurs when sunlight is refracted through hexagonal ice crystal high in the atmosphere. It is one of the commonest sky phenomena there is. Here is a few images I've made of halos around the Moon.
It's nice and all the speculate, but couldn't have someone asked a meteorologist before getting all Stargate on us.
The Nibiru crowd are getting excited about the bright blob near the sun, claiming it's a winged disk.
Well, one thing it's not is Venus, on January 4, when this image was taken in Indonesia, Venus was 47° away from the Sun, well outside the 22° radius of the halo (as was Mercury, but usually Venus and occasionally Jupiter are bright enough to to photograph in daylight).
Most likely (in no particular order) are, a parhelion from a parhelic circle crossing a dimmer, internal halo that doesn't show up on the photo (see here for a complex halo, and other images here and here), a random flare off high atmospheric ice crystals or internal camera lens flare.
But a planet it is not.
And why the author of the piece thought that a halo in Indonesia was responsible for bird kills in the US is beyond me. I did like the idea that sonic booms from the "intense seasonal meteors" could be responsible for bird kills, the Quadrantids are quite modest (nice picture here), and we don't see more die off's during the Geminids for example.
There's a really simple explanation for the bird die off's, it's just normal seasonal die-off's, blown out of proportion by media attention.
Labels: Halo, scepticism
Wednesday, June 23, 2010
Yet another Ring Around the Moon
While I was a little disappointed that cloud had stopped me seeing Venus near the Beehive cluster, when returning from bread shopping last night (3 boys can go through a LOT of bread), I looked up to see a prefect halo around the Moon. Absolutely brilliant and like the ISS pass I saw, makes my point about keeping on looking up).The family, watching Master Chef in the warmth of the Living Room, were not excited, but MiddleOne did come out and express delight.
This is a great example of a 22 Degree halo. 22 Degree halos are the commonest kind of halo or arc seen in the sky, although they are far less obvious than rainbows, and may easily be missed.
22 Degree halos are formed by refraction of light through hexagonal columar ice crystals as they fall to the ground. The halo will form when there is a uniform distribution of randomly oriented crystals in the cirrostratus cloud through which the Moon (or Sun) is shining. Because random orientation is only possible if the crystals are tumbling as they fall, the crystals need to be quite small. This is different from what I've been calling "Moonbows", there are typically 8 degrees away from the Moon, and are caused by bullet shaped crystals.
The image above was made by stitching together two separate shots, as the halo was too bigh to fit into the camera field of view.
Saturday, October 31, 2009
A Ring Around The Moon
Jupiter forms the jewel in this ring around the Moon (click to embiggen)Even on cloudy nights you can see interesting things, I captured this image of a ring around the Moon on a night you might have thought was a waste of time. Technically its a 22 degree halo, not a ring, and fortuitously the halo arc was so close to Jupiter that it looked like a Jewel in the ring. In the original you can see a little colour in the halo.
22 Degree halos are the commonest kind of halo or arc, although they are far less obvious than rainbows, and may easily be missed. They are formed by refraction of light through hexagonal columar ice crystals as the fall to the ground. The halo will form when there is a uniform distribution of randomly oriented crystals in the cirrostratus cloud through which the Moon (or Sun) is shining. Because random orientation is only possible if the crystals are tumbling as they fall, the crystals need to be quite small. This is different from what I've been calling "Moonbows", there are typically 8 degrees away from the Moon, and are caused by bullet shaped crystals.
So not only are you seeing something pretty, you are seeing a dynamic event and some cool physics.
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