Starship Asterisk*

PeterR wrote:Hello everyone,
I am the author of this picture (...) There is a famous painting called "Vädersoltavlan" depicting an intricate halo over Stockholm in 1535. It is also the oldest known representation of Stockholm.
My photograph is not from the same spot and not exactly in the same direction but otherwise I think it may be an interesting parallel: http://en.wikipedia.org/wiki/V%C3%A4dersolstavlan and http://www.atoptics.co.uk/fz346.htm

/*Peter Rosén

Chris Peterson wrote:The best halo displays involve lots of ice crystals in the air. It's no coincidence that so many of these excellent halo images are taken from polar or near polar locations.!

Céline Richard wrote:Do you know if there are places on Earth, where we would be more likely to admire a halo, compared with other places?

Chris Peterson wrote:You can see exactly this with your own eyes when the conditions are right, and it will look very similar to what the image shows.

Some people get very upset at the idea of composite digital images. But the reality is, our eyes have orders of magnitude wider dynamic range than the best cameras.You can stand in sunlight and clearly see detail in both the brightest and the most shadowed areas- something that no camera can do. (In reality, there is more than your eyes involved here- your brain actually builds up an image as your eyes move around. Yes! What you see with your own eyes is also a composite, both of exposure and a mosaic.)

It is possible to make an image that comes closer to visual reality by taking several exposures and combining them cleverly. Tools for doing this are routinely available in image processing software, and some cameras now take two or more images in quick succession and silently combine them into a single image before you ever see it.

I don't know if this image is such a composite, but I do know that this type of shot usually produces a more realistic image when composited from multiple exposures, and I also know that the image quite accurately represents the true visual appearance of a halo display.

Céline Richard wrote:You say this picture could be a hydride of two, with different exposure? I thought i could see this in the sky for real!

wwcsig wrote:It's a stunning and beautiful picture, no doubt. But shouldn't the fact that this is obviously a composite of at least two pictures with different exposure settings be mentioned? A shot right into the sun that has even the shadows on the sides of the buildings correctly exposed is hardly possible. Doesn't the combination of the multiple images distort the actual halo it is depicting?

http://www.ursa.fi/blogit/ice_crystal_h ... p?m=200802
http://www.ian.cz/redsys/upload/631-380.jpg

Manu61 wrote:
This photo looks like featuring a much more rare phenomenon: the 44° parhelia (actually secondary 22° sundogs from very bright sundogs).

There is also a hint of something tangent at the 22° halo top.

http://en.wikipedia.org/wiki/Upper_tangent_arc wrote:

http://vjac.free.fr/skyshows/icehalos/icehalos.html

<<An upper tangent arc is a halo, an atmospheric optical phenomenon which appears over and tangent to the 22° halo around the sun.

The shape of an upper tangent arc varies with the elevation of the sun; while the sun is low (less than 29–32°) it appears as an arc over the sun forming a sharp angle. As the sun rises, the curved wings of the arc lower towards the 22° halo while gradually becoming longer. As the sun rises over 29–32°, the upper tangent arc unites with the lower tangent arc to form the circumscribed halo.

Both the upper and lower tangent arc form when hexagonal rod-shaped ice crystals in cirrus clouds have their long axis oriented horizontally, while otherwise rotated in any direction. This orientation of the crystals also produces other halos, including 22° halos and sun dogs, but a predominant horizontal orientation is required to produce a crisp upper tangent arc. Like many other halos, upper tangent arcs grade from a red inner edge to a blue outer edge because red light is refracted more strongly than blue light.

royalpalms6 wrote:When are we going to see photos of SPACE?

Hofi wrote:If you look closely, you can even find another ring outside the main ring.
It lies about twice the radius of the main ring and is especially visible on
the horizon.

If you cannot see the second ring, try to watch your screen from another angle than
usually. (f.i. from the side). Then, the ring comes out more clearly...

APOD Robot wrote:Also visible is the bright 22 degree halo -- as well as the rarer and much fainter 46 degree halo

http://en.wikipedia.org/wiki/Bertil_Lindblad wrote:
<<The Stockholm Observatory is an astronomical institution in Stockholm, Sweden, founded in the 18th century and today part of Stockholm University. The first observatory was established by the Royal Swedish Academy of Sciences was begun in 1748, and the building was completed in 1753. It is situated on a hill in a park nowadays named Observatorielunden.

Adriaan van Maanen (left) & Bertil Lindblad (center)
on the platform for observation at the
Newton focus of the 1 meter reflector of the
Stockholm Observatory in Saltsjöbaden 1938.

Bertil Lindblad (Örebro, 26 November 1895 – Saltsjöbaden, 25 June 1965) was professor and astronomer of the Royal Swedish Academy of Sciences and head of the Stockholm Observatory from 1927 to 1965. Lindblad was responsible for the observatory's move from the old building in the centre of Stockholm to a newly built facility outside of Stockholm in Saltsjöbaden (Salt bath) in 1931.

Lindblad studied the theory of the rotation of galaxies. By making careful observations of the apparent motions of stars, he was able study the rotation of the Galaxy. He deduced that the rate of rotation of the stars in the outer part of the galaxy, where the Sun is located, decreased with distance from the galactic core. A certain class of resonances in rotating stellar or gaseous disks are named Lindblad resonances, after Bertil Lindblad.

A Lindblad resonance is an orbital resonance in which an object's epicyclic frequency is a simple multiple of some forcing frequency. Resonances of this kind tend to increase the object's orbital eccentricity and to cause its longitude of periapse to line up in phase with the forcing. Lindblad resonances drive spiral density waves both in galaxies and in Saturn's rings.

Lindblad resonances affect stars at such distances from a disc galaxy's centre where the natural frequency of the radial component of a star's orbital velocity is close to the frequency of the gravitational potential maxima encountered during its course through the spiral arms. If a star's orbital speed around the galactic centre is greater than that of the part of the spiral arm through which it is passing, then an inner Lindblad resonance occurs - if smaller, then an outer Lindblad resonance. At an inner resonance, a star's orbital speed is increased, moving the star outwards, and decreased for an outer resonance causing inward movement>>

bystander wrote:

Indigo_Sunrise wrote:

royalpalms6 wrote:When are we going to see photos of SPACE?

Come back tomorrow.......

But there won't be anything to complain about, then.

Indigo_Sunrise wrote:

royalpalms6 wrote:When are we going to see photos of SPACE?

Come back tomorrow.......

royalpalms6 wrote:When are we going to see photos of SPACE?