A 22° halo is an optical phenomenon whereby a large ring or halo is formed 22 degrees around the sun. Light is refracted in hexagonal ice crystals in the cirrus clouds. Red light is refracted 21.54° and blue light 22.37°. This wavelength-dependent variation in refraction causes the inner edge of the circle to be reddish while the outer edge is bluish. The centre of the ring is often darker because no light is refracted beyond the red line. 22 degree halos are often thought to be a warning of approaching storms because the cirrus clouds in which they form are often present a few days before a weather change.
Image: 22° halo around the sun in southern Victoria, credit Alex Jaeger
This is a picture of the relative sizes of the moon and the Andromeda Galaxy as seen from earth, and it shows what the Andromeda Galaxy would look like if it were brighter. The Andromeda Galaxy is the closest spiral galaxy to our own Milky Way Galaxy and it is 2.5 million light years distant. Galaxies are mostly empty space and the stars in them stretch out over a great distance. We can only see Andromeda’s galactic centre as a small fuzzy patch in the sky, the rest is far too faint to see with the naked eye. The Moon is about the width of your thumb at arms length, and if the Andromeda Galaxy were brighter it would appear about six times as long as the moon.
Fractals are patterns that are self-similar across different scales. They are created by repeating a simple process over and over through a feedback loop. Fractals are the visualisation of dynamical systems and they exist between our familiar dimensions. This is called the fractal dimension. Fractal patterns are familiar, since nature is full of fractals. For instance: trees, rivers, coastlines, mountains, clouds, seashells, hurricanes, etc. Abstract fractals - such as the Mandelbrot Set - can be generated by a computer calculating a simple equation over and over. And this creates an infinitely diverse pattern.
Just to put our place in the universe into perspective, An animation of a photo of a tiny area of sky that appears empty to the naked eye, This is the Hubble ultra deep field image.. each smear and fuzzy spot is a galaxy, billions of light years away, containing billions and billions of stars, many like our own sun, with planets and possibly life. How small and vulnerable are we.. and how grand is the universe?
"The scientific man does not aim at an immediate result. He does not expect that his advanced ideas will be readily taken up. His work is like that of the planter — for the future. His duty is to lay the foundation for those who are to come, and point the way. He lives and labors and hopes."
This is the “spinning Dancer” Illusion. What direction does she appear to spin? You may be surprised the image isn’t spinning at all, it is all a trick of the mind.
Some people will see the dancer spin clockwise, others counter-clockwise. It is also possible to see the direction change intermittently. Try to blink your eyes, or focus on a particular feature. You may suddenly see her jump directions..
It has been suggested that the perception of the spin direction is a personality test to see if the person is right- or left brained, but this is incorrect. The illusion is called a bistable perception, meaning the 2-dimensional figure can be seen from two different perspectives. Because there is no third dimension, our brains try to construct a 3-dimensional space around the figure.
The beautiful fractal world of the prehistoric Ammonite
The Ammonite is an extinct marine creature distantly related to the Nautilus. Ammonites are cephalopods and first appeared in the seas 415 million years ago, They are related to the octopus and squid. During their evolution three catastrophic events occurred and they became extinct around 65 million years ago. Ammonites could ranged in size from very small to extremely large.
Ammonite shells are composed of compartments that are connected with sutures. These suture lines are intricate fractals and very beautiful. The complexity of the suture lines have puzzled scientists and it is believed that the complexity of the design added to the strength of the shell. The Ammonite may have lived at a great depth in the ocean.
Throughout history the Ammonite has been an inspiration to artistic design. In medieval times they were believed to be snakes that were turned to stone.
These images look like exotic phyto-plankton, but in fact they are boundary of different Julia sets. Julia sets are mathematical fractals. The same pattern repeats infinitely in smaller and smaller detail. Following the same simple rules repeatedly, these amazing patterns are formed.
This is a fractal resembles a dragon and is also known as the Jurassic Park Fractal. Starting from a base segment, replace each segment by 2 segments with a right angle and with a rotation of 45° alternatively to the right and to the left. Continue this with the newly generated segments.
The distances between galaxies are enormous and galaxies contain on average 100 billion stars. You may think a collision between galaxies is catastrophic, given the enormous number of stars, but the chance that individual stars collide is extremely small. This is because the density of stars in a galaxy is very low. Galaxies span huge distances and stars in colliding galaxies pass through each other without colliding. It is the dust between the stars that heats up and forms new stars. A collision between galaxies may take tens of millions of years as the galaxies spin around each other in a gravitational dance. Eventually they may merge to form a larger galaxy. The image shows snapshots of galaxies that are in the process of colliding. Stars are being strung along as the galaxies move slowly through each others gravitational field. We cannot see the movement in these images, but scientists use computer models to predict how galaxies move. The images are taken by the Hubble Space Telescope.