Thursday, January 17, 2008

An explanation for the multiple rainbows

Spaceweather.com have posted an explanation for the bizarre multiple rainbows I saw last Saturday afternoon. According to Atmospheric Optics expert Les Cowley the explanation is:

"The multiple arcs are called supernumerary rainbows. They were so named because early natural philosophers could not explain them and considered that they should not be there. They are a diffraction pattern produced when rays passing through small raindrops overlap and interfere. If we are lucky we see one or two, these widely spaced multiple ones are exceptional and tell us that the raindrops were very small and, more unusually, all of the same size."

Who knew?

Sunday, January 13, 2008

Strange rainbow


Yesterday afternoon I noticed this bizarre rainbow in the sky, I have never seen anything like it before. It wasn't just a double rainbow, but there were at least 6 bows visible, but getting smaller and fading into the distance. I took these photos around 4:00pm yesterday afternoon looking east in Vancouver, BC.

Here's another slightly closer view, and following that a contrast enhanced version which more clearly shows the bows. Bizarre! Has anyone else seen anything like this before?



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Thursday, January 10, 2008

Four big earthquakes off the NW coast

We all know that the area around Pacific North-West is a potential hot spot for earthquakes. Yet, it is still surprising when we get four quakes with a magnitude of greater than M6 in less than a week! Fortunately, none of the quakes were on the land. Three of the quakes have been situated just south of the Queen Charlotte Islands, BC and the most recent off the coast of Oregon:

MAP 6.4 2008/01/05 11:44:48


QUEEN CHARLOTTE ISLANDS REGION
MAP 6.6 2008/01/05 11:01:05


QUEEN CHARLOTTE ISLANDS REGION
MAP 6.1 2008/01/09 14:40:01


QUEEN CHARLOTTE ISLANDS REGION
MAP 6.3 2008/01/10 01:37:19


OFF THE COAST OF OREGON

Hopefully this isn't a harbinger of things to come and any further big shakes stay out at sea and don't wander landward.

Hubble Finds Double Einstein Ring



The Hubble Space Telescope has revealed a never-before-seen optical alignment in space: a pair of glowing rings, one nestled inside the other like a bull's-eye pattern. The double-ring pattern is caused by the complex bending of light from two distant galaxies strung directly behind a foreground massive galaxy, like three beads on a string. This very rare phenomenon can offer insight into dark matter, dark energy, the nature of distant galaxies, and even the curvature of the universe. The phenomenon, called gravitational lensing, occurs when a massive galaxy in the foreground bends the light rays from a distant galaxy behind it, in much the same way as a magnifying glass would. When both galaxies are exactly lined up, the light forms a circle, called an "Einstein ring," around the foreground galaxy. If another background galaxy lies precisely on the same sightline, a second, larger ring will appear. The massive foreground galaxy is almost perfectly aligned in the sky with two background galaxies at different distances. The foreground galaxy is 3 billion light-years away. The inner ring and outer ring are comprised of multiple images of two galaxies at a distance of 6 billion and approximately 11 billion light-years. The odds of seeing such a special alignment are estimated to be 1 in 10,000.

The Violent Lives of Galaxies: Caught in the Cosmic Dark Matter Web


Astronomers are using NASA's Hubble Space Telescope to dissect one of the largest structures in the universe as part of a quest to understand the violent lives of galaxies. Hubble is providing indirect evidence of unseen dark matter tugging on galaxies in the crowded, rough-and-tumble environment of a massive supercluster of hundreds of galaxies. Dark matter is an invisible form of matter that accounts for most of the universe's mass. Hubble's Advanced Camera for Surveys has mapped the invisible dark matter scaffolding of the supercluster Abell 901/902, as well as the detailed structure of individual galaxies embedded in it. The image, taken by NASA's Hubble Space Telescope, shows the supercluster. The magenta clumps throughout the image reveal the distribution of dark matter in the cluster. The galaxies lie within the clumps of dark matter. The image was assembled by combining a visible-light image of the supercluster taken with the MPG/ESO 2.2-meter telescope in La Silla, Chile, with a dark matter map derived from Hubble observations.



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