APOD: An Unusual Venusian Oval (2012 Feb 13)

[APOD Robot]

An Unusual Venusian Oval

Explanation: Why would Venus appear oval? Venus has been seen countless times from the surface of the Earth, and every time the Earth's atmosphere has dispersed its light to some degree. When the air has just the right amount of dust or water droplets, small but distant objects like Venus appear spread out into an angularly large aureole. Aureoles are not unusual to see and are frequently noted as circular coronas around the Sun or Moon. Recently, however, aureoles have been imaged that are not circular but distinctly oval. The above oval Venusian aureole was imaged by the astrophotographer who first noted the unusual phenomenon three years ago. Initially disputed, the unusual distortion has now been confirmed multiple times by several different astrophotographers. What causes the ellipticity is currently unknown, and although several hypotheses hold that horizontally oriented ice crystals are responsible, significant discussions about it are still taking place.

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[DNA]

could it be possible that the magnetic field of the earth could cause charged ice crystals to align in a particular way?

[Guest]

On January 24, 2012, I have imagined Venus near Moon and Venus appeared oddly lenticular - http://ngc6543.files.wordpress.com/2012 ... _0544s.jpg (I have several other images).

[Aphosis]

Maybe:
Because Venus is one of the inner planets, it is almost always partial lightend and looks often just like our moon, with its typical oval "moon" shape. Pictures taken her on earth could give it an Oval look.
The times Venus is not oval, for example when its on our side of the sun or the total opposite, we cannot see Venus, because its either stil day light or the sun is blocking its view.
The time we can see venus in front of the sun is rare, 6 June 2012 is the next occasion.

[Guest]

Actually this phenomenon has been found over ten years ago. For example, there is a discussion about this in Finnish usenet-site, archived by google: http://groups.google.com/group/sfnet.ha ... 71a78d67ba, in Finnish - try Google Translate. I have seen this phenomenon several times over the last ten years.It can sometimes be seen also around Jupiter, I have a couple of photos of this - so the the phase of Venus have no significant effect.

Pertti Rautiainen
Department of Physics/Astronomy Division
Oulu, Finland

[nstahl]

Is this phenomenon hard enough to see that it may always have been happening but just was missed, or is it likely to actually be a new phenomenon (a few decades old at most)? If the latter, what are we doing to our air?

[Guest]

Is this phenomenon hard enough to see that it may always have been happening but just was missed, or is it likely to actually be a new phenomenon (a few decades old at most)? If the latter, what are we doing to our air?

Based on my own observations, it is quite dim around Jupiter, but around Venus it can be so bright that I don't understand how it could have been missed. One possible explanation is the location: I live at latitude 65 North - perhaps these ovals are seen more often around here? Perhaps some reference to this phenomenon could be found from the diaries of Polar explorers?

Pertti Rautiainen
Department of Physics/Astronomy Division
University of Oulu
Finland

[saturn2]

An unusual distortion in Earth´s atmosphere.
The light from Venus to arrive Earth with a oval aureole.

[Byork]

Aureole-oval must be a non-terrestrial event caused by cloud of particles and gas moving though Solar System. Alternatively, it could also signal movement of solar system into a region of the Milky Way Galaxy (such as galactic equatorial plane) with above average occurance of dust and gas. Maya probably predicted long ago that this would happen in 2012. Thus, galactic meteors and asteroids may be expected to merge with the Earth, and Solar System in general, throughout the year. Other implications of such celestial mechanics would likely be a very severe winter and mild summer

so, hold on folks !

its gonna be rough riding for a while

we're all in this together

[Les Cowley]

Oval Venus (http://www.atoptics.co.uk/fz196.htm) and Jupiter (http://www.atoptics.co.uk/fz505.htm) aureoles are an atmospheric effect. Most likely they are diffraction (http://www.atoptics.co.uk/droplets/corform.htm) by aerodynamically oriented ice crystals high in cirrus and altostratus cloud ( http://www.atoptics.co.uk/fz732.htm ). Similar ice crystals form halos. If so formed they could be observed anywhere. A test of the diffraction mechanism would be to photograph aureoles around high and near horizon bright stars under the same cloud conditions (i.e. near simultaneously!). High stars should have more circular aureoles than ones lower in the sky.

A challenge for astrophotographers out there!

Les Cowley
Atmospheric Optics - http://www.atoptics.co.uk
Optics Picture of the Day - http://www.atoptics.co.uk/opod.htm

[Semjase]

Would the oval have anything to do with Venus being in the phase of quarter or half? This image of Venus seems to be full/circular, but it is so distant, the phases of Venus are almost indiscernable to the amateur (such as myself).

[orin stepanek]

Nice catch Doug; your picture does a nice job illustrating the oval glow around Venus.

[mike redfern]

There is an atmospheric phenomenon called a sub-sun which can be observed from an aircraft flying through a thin cloud of ice crystals. One can observe a specular image of the sun below the horizon by the same angle as the sun is above it. The explanation given is that ice crystals form in thin sheets which are maintained in a horizontal position by aerodynamic forces and one observes reflections from these sheets. see http://en.wikipedia.org/wiki/Subsun

I think that the "Venus Effect" is due to a similar phenomenon. If there are ice crystals which are predominantly oriented horizontally then reflections would elongate the image in a vertical direction.

This explanation would be open to experimental verification.
(a) the effect would get bigger as the altitude of Venus increases
(b) detailed examination of the isophotes might show an asymmetrical effect, with the top being brightest

[Les Cowley]

Would the oval have anything to do with Venus being in the phase of quarter or half? This image of Venus seems to be full/circular, but it is so distant, the phases of Venus are almost indiscernable to the amateur (such as myself).

No. On the scale of the ovals, Venus is acting as a point source of light. Venus is overexposed in the image - it had to be to reveal the oval. And Jupiter shows similar ovals also.

Les Cowley
Atmospheric Optics - http://www.atoptics.co.uk
Optics Picture of the Day - http://www.atoptics.co.uk/opod.htm

[Les Cowley]

I think that the "Venus Effect" is due to a similar phenomenon. If there are ice crystals which are predominantly oriented horizontally then reflections would elongate the image in a vertical direction.

This exact effect above has already been seen many times - It is a Venus pillar (http://www.atoptics.co.uk/halo/venpill.htm). The sun, moon and artificial lights form similar pillars. But pillars are a quite separate phenomena that look different and are far more elongated than small ovals with red fringed edges. The ovals are a diffraction rather than a reflection/refraction effect.

Les Cowley
Atmospheric Optics - http://www.atoptics.co.uk
Optics Picture of the Day - http://www.atoptics.co.uk/opod.htm

[Guest]

Anyone ever think it could be as simple as: Venus is in a "Waning Gibbous" p hase with a humid Earth's atmosphere??

[noozoo]

I think it must be the aliens.

[keith evans]

I agree with Les. It's a pillar probably from a sub-visual cirrus cloud.

[Chris Peterson]

Anyone ever think it could be as simple as: Venus is in a "Waning Gibbous" p hase with a humid Earth's atmosphere??

Yes... and it has already been dismissed. Please read the discussion before commenting.

[geomousey]

No need to be testy, Chris. Many amatures read this board and would like to feel welcome to participate. Pehaps, if you lack the patience to deal with this, you could post your opinions in a private message or forum and invite those who share your disdain for the uninformed yet curious and wonderous.

I'm sure the idea that it had to do with 'phase' was first in most people's minds.

[geomousey]

http://www.atoptics.co.uk/fz505.htm
provides a good explanation

[Chris Peterson]

No need to be testy, Chris. Many amatures read this board and would like to feel welcome to participate. Pehaps, if you lack the patience to deal with this, you could post your opinions in a private message or forum and invite those who share your disdain for the uninformed yet curious and wonderous.

No. I intend to be testy when people don't have the good manners to read through a discussion before posting their own theories. It wastes everyone's time, and makes the discussion hard to follow. It's always a problem when we have these "mystery" images- if the threads get long, we end up with the same discredited "theories" posted over and over and over.

I'd argue for a moderator simply deleting any posts that repeat what has already been said. In the absence of that, my opinion is that anybody smart enough to contribute here is smart enough to read what has already been said. Otherwise, I don't encourage their participation.

[Guest]

http://www.atoptics.co.uk/fz505.htm
provides a good explanation

great find!

[Soviet Mike2012]

Hi all:

My boss explaination:

My guess is that oriented ice crystals are responsible, however slightly
different than the solar pillar. In the solar pillar the plates are large
enough that they are quite horizontal producing the straight shaft of
reflected light. For this Venus picture either the plates so small that
Brownian motion is causing a distribution of orientations away from
horizontal or the turbulence is so intense to cause orientation
fluctuations on the millimeter scale. The reason we don't see a Venusian
pillar is that large plates occur in very low number concentrations and so
there is not enough light from Venus to make it visible. Feel free to
distribute this explanation.

Cheers

Glen Lesins
Associate Professor (Research)
Department of Physics and Atmospheric Science
Dalhousie University
Halifax, NS, Canada B3H 3J5
Email: glen.lesins@dal.ca

[owlice]

http://www.atoptics.co.uk/fz505.htm
provides a good explanation

great find!

Well, sure; that's why it's one of the links in the APOD text....