Rainbow/Moonbow – A Colorful Post!

A rainbow is caused by reflection of light in water droplets in the atmosphere, resulting in a spectrum of light appearing in the sky in the form of a multicolored arc. Now this much we probably all know, but here are some interesting facts about this beautiful natural phenomenon which you may not know:

Position/Angle: A rainbow is not an object located at a specific distance, thus it cannot be physically approached. It is impossible for an observer to move himself into a position to see the rainbow from any other angle other than the customary 42 degrees from the direction opposite the sun. If you see someone closer to a rainbow, as in you see them under the rainbow you are seeing, they will be seeing a different rainbow further away maintaining the same angle of viewing.

Center: A rainbows center is at the shadow of the observers head (the antisolar point). The bow then forms a circle with an angle of 42 degrees to the line between the observers head and the shadow of his head. If the sun itself is higher than 42 degrees then the rainbow usually cannot be seen as it falls behind the horizon. Exceptions to this can occur when the observer is high up compared to the horizon (in a plane, or up a mountain).

Colors: A rainbow spans a complete, continuous spectrum of colors. Any distinct bands of color we see are from our own color vision capabilities. When viewed in black & white a rainbow doesn’t have any bands and it is a continuous gradient.

Double Rainbow: A double rainbow has a second arc seen outside of the main arc with the order of its colors reversed. The second rainbow is caused by light reflecting twice inside the water droplets. For this second rainbow to be seen decently a dark background is required (a dark cloud behind the rainbow) otherwise the second rainbow is quite faint and may not be visible.

Best Viewing: The best view of a rainbow is when half the sky is still dark with raining clouds and the viewer is under clear sky in the direction of the sun. The result is a really bright rainbow contrasting with the dark background.

Supernumerary Rainbow (Stacker Rainbow): A very rare phenomenon consisting of several faint rainbows on the inside of the primary one. Their pattern doesn’t fit the usual color band and cannot be explained with classical geometric optics. They are caused by interference between rays of light, because the light follows slightly different paths varying in length. The very existence of supernumerary rainbows proves the wave nature of light and was exemplified and explained by Thomas Young in 1804, making them highly significant. An example of one: https://haplofromnexus.files.wordpress.com/2012/11/edit-600×398.jpg

Moonbow: Also known as a lunar rainbow is a rainbow produced by the light reflected off the moon, rather than direct sunlight. They are thus significantly faint and hard to see. Here is an example: https://haplofromnexus.files.wordpress.com/2012/11/moonbow.jpg

“A colored circle around the moon is not a moonbow—it is usually a 22° halo produced by refraction through hexagonal ice crystals in cirrus clouds”

Here are some links to read more about these subjects,
Mete.

Links:
http://eo.ucar.edu/rainbows/
http://www.atoptics.co.uk/rainbows/supers.htm
http://www.ratestogo.com/blog/moonbows/

Carotenaemia (Turning Orange! – or Blue?!)

You know that myth about how if you eat too many carrots you’ll turn orange?

Well actually, it’s not a myth, there is even a scientific explanation for this condition known as Carotenosis. It results from the excess intake of the orange pigment in the blood, carotene. Food with high levels of Carotenoids are primarily carrots but there are many other foods which have these including many other vegetables, eggs, cheese etc. Carotenoids contribute to normal appearing human skin color and they also contribute to a significant amount of ultraviolet protection.

The condition identified as Carotenaemia is more notably visible in light skinned people as a orange discoloration of the skin. In more dark skinned people it can be identified from the palms of the hands instead. It is a benign condition commonly occurring in vegetarians and children, it is harmless and does not require treatment. Stopping the intake of Carotenoid heavy food will allow the skin color to turn back to normal.

Argyria:
A similar condition resulting from the excessive consumption of elemental silver, silver dust or silver compounds. It results in the skin turning a bluish-grey color. However, Argyria is an irreversible process unlike carotenaemia. People with this condition are humorously referred to as the real smurfs, because they are actually blue. A famous example is Stan Jones an american politician. If you type his name into Google Images you can see the Argyria condition he is suffering from.
Mete.

To read more about this stuff:
http://emedicine.medscape.com/article/1104368-overview
http://en.wikipedia.org/wiki/Argyria

Gamma Ray Burst (The brightest event to occur in the Universe)

“They represent the most powerful explosions of energy in the cosmos since the Big Bang itself, corresponding to the equivalent of a thousand Earths vaporized into pure energy in a matter of seconds”

HEY OKAY LISTEN UP, now this is one of the most powerful/amazing things in the universe, if not thie most powerful! A gamma ray burst is the brightest elecromagnetic event known to occur in the entire universe. So it is well worth reading about, specially on a cold rainy November day..

Brief Description: A GRB (Gamma ray Burst) is a short lived burst of gamma-ray photons. Bursts can last from about 10 milliseconds to a few minutes. Gamma ray bursts shine hundreds of times brighter than a typical supernova explosion and about a million trillion times brighter than the sun, making them briefly the brightest source of photons in the observable universe. A typical burst releases as much energy in a few seconds as the Sun will in its entire 10-billion-year lifetime!! This is just mind-blowing to imagine… GRB’s consist of a narrow beam of radiation released during a supernova, as a massive star collapses into a neutron star, quark star of a black hole. This energy is released along the axis of rotation in the form of a Gamma Ray Burst.

No known process in the Universe can produce this much energy in such a short time. However, gamma-ray bursts are thought to be highly focused explosions, with most of the explosion energy collimated into a narrow jet traveling at speeds exceeding 99.995% of the speed of light.

GRB and Us: All observed gamma-ray bursts have been from outside the milkyway galaxy. It has been hypothesized that a gamma-ray burst in our own galaxy (The Milky Way) pointing directly towards us would cause a Mass Extinction event. GRB’s occur at a detected rate of about one per day in the universe, making the possibility of one occurring in any one specific galaxy about one per 500.000 years. If one did occur in the Milky Way Galaxy all planets lying in the two cones of radiation (the two oppositely directed jets of energy) on either side would have all life wiped out.

Here is an educational song on the subject of Gamma-ray Bursts:
http://www.youtube.com/watch?v=Cco7D8Cc_6Y

Take care,
Mete.

Links for reading more about this incredible phenomenon:
http://astro.berkeley.edu/research/grbs/grbinfo.html
http://www2.astro.psu.edu/users/nnp/grbphys.html
http://news.nationalgeographic.com/news/2009/04/090403-gamma-ray-extinction.html
http://imagine.gsfc.nasa.gov/docs/science/know_l1/bursts.html

Spontaneous Human Combustion (SHC)

Spontaneous Human Combustion: is the burning of a living person without an external source of ignition. There have only been about 200 cited cases ever, world-wide. There are several different theories attempting to explain this weird phenomenon. Some of the theories revolve around paranormal explanations (divine intervention, ghosts etc..). Some other more natural explanations are of either a certain unknown body chemistry going on (raised level of blood alcohol, production of concentrated gas, not drinking enough water, smoking…) or of a natural disaster incident (for example the victim being drunk and dropping a cigarette). Even further natural explanations suggest high energy particles or gamma-rays as the cause of SHC.

After extensive research on the subject the most widely accepted explanation is the “Wick Effect”.
This is a cyclic process in which the victim burns through his/her own fats, until complete combustion. A person wearing clothes acts like an inside out candle, with the wick being the clothing, and the fuel being the fat(flesh) inside the clothing. Hence there is a continuous supply of fuel as the fat seeps through the clothing creating a cyclic process. For this process to initiate there obviously has to be an initial ignition though, in most cases there has been such a source present somewhere in the room.

So basically: After a tiny ignition, the human body contains enough fuel in the form of fat (hydrocarbons) to completely burn itself to ashes.

It takes a very hot flame to reduce a human body to ash. Crematoriums have special chambers designed for it. However, in almost all combustions, there’s no burns in the room around the body, indicating that the person simply stayed in one place. Whatever the cause of this combustion, it seems to knock people out first.

*The reason the object (the couch the person is sitting on) goes pretty much undamaged while the person is incinerated is because fire burns upwards. These materials also help retain the melted fat even further aiding the cyclic burning process.

Which ever theory you like to believe, this phenomenon is surely quite spectacular,
Mete.

Further Links on the “Wick Effect” and SHC:
http://io9.com/5855700/10-cases-of-spontaneous-human-combustion
http://www.dbskeptic.com/2009/02/28/spontaneous-human-combustion-and-the-wick-
effect/
http://en.wikipedia.org/wiki/Spontaneous_human_combustion

Famous Photographs: Pillars of Creation

Description: “Pillars of Creation” is a photograph taken by the Hubble Telescope in 1995. It shows elephant trunk like columns of interstellar gas from the Eagle Nebula (7000 light years away). The reason they are called the pillars of creation is because the gas and dust pictured is in the process of forming/creating new stars. It was named one of the top 10 photographs taken by the Hubble.

Further Facts:
*The pillars are composed of molecular hydrogen that is being eroded from the ultra-violet light of nearby “hot” stars. The pillar on the left is 4 light years in length. The little finger-like things on the very end of the clouds are bigger than our entire solar system.

*Because they are 7000 light years away we are viewing them as they were 7000 years ago, there has been evidence of a supernova explosion in the nearby region that would have destroyed the clouds about 6000 years ago, meaning we will see them being destroyed about 1000 years from now.

*If you could go back about 4.5 billion years and watch our own solar system form you would see a sight similar to this.

Further Reading:
http://www.pbs.org/wgbh/nova/origins/hubb-16.html
http://csep10.phys.utk.edu/astr162/lect/birth/proto.html

A moment in history (July 1941)

In July 1941 Maximilian Kolbe volunteered to die in place of a stranger.

In the Auschwitz Nazi German Concentration Camp there had been an escape incident of 3 prisoners of war, this prompted the SS deputy camp commander to randomly pick 10 men to be starved to death so as to deter further escape attempts. One of the selected men lamented his wife and children, and so Maximilian Kolbe volunteered to take his place. He was placed in Block 13 (notorious for torture) to starve to death. He led the other men with song and prayer, encouraging them all along, he was eventually the only man alive after two weeks and was killed with a lethal injection of carbolic acid because the guards needed the cell emptied.

“Men like Maximilian Kolbe shine forth like beacons during mankind’s darkest moments”

In 1982 he was canonized and declared a martyr of charity.
Have a nice day,
Mete.

Further Reading:
http://auschwitz.dk/Kolbe.htm

The Karman Line (The Official Edge of Space!)

Have you ever wondered where “outer space” officially begins?
The Karman Line lies at about 100km above the surface of the Earth and it is commonly used to identify the boundary between the Earth’s atmosphere and Outer space. It is the defining boundary between aeronautics and astronautics. This is the altitude above which a vehicle wishing to fly would have to fly at a speed greater than the orbital velocity to derive sufficient lift to be able to support itself.

Orbital Velocity: For an orbiting object to be able to stay airborne and orbit the Earth it is required to have a certain centrifugal velocity to balance the downward pull of gravity and keep it in orbit.

Explanation: So basically at just about that altitude the velocity required to generate enough lift to not fall (because the atmosphere/air is so thin up so high) surpasses the orbital velocity of an object. The thinner the air, the faster the object has to go to generate enough lift to stay up. So this height is chosen as the border of space as it is a defining height in this aspect. Quite an exotic definition. Also 99.99997% of the atmosphere (by mass) lies beneath this height, but obviously the atmosphere has no upper boundary, it just gets thinner and thinner, gradually fading away. We can safely say that nearly the entire atmosphere is below this line though.

Trivia: Felix Baumgartner did not actually jump from “outer space” on the 14th of October when he passed the speed of sound, he in fact jumped from 39km above ground level.

Trivia: The first vehicle ever to cross the Karman Line and venture into outer space is the V2 Rocket. (A short range ballistic missile developed during the Second World War in Germany). The first man-made thing ever to enter outer space that is!! The V2 rocket is also the ancestor of ALL modern rockets, making it highly important.

Trivia: Aurora’s (explained a few posts ago) occur at approximately this height in the thermosphere.

Trivia: An astronaut is defined as anyone having crossed this line.
Have fun,
Mete.

Links for further reading on this topic:
http://www.fai.org/icare-records/100km-altitude-boundary-for-astronautics
http://en.wikipedia.org/wiki/K%C3%A1rm%C3%A1n_line
http://www.stanford.edu/~xuanwu/v2/

Geomagnetic Reversal (Mass-Extinction here we come!)

What is a Geomagnetic Reversal?
A Geomagnetic Reversal (Reverse Polarity) is a flip of the Earth’s North and South Magnetic Poles (They change places). This phenomenon occurs on average once every 450.000 years, the reversal process itself taking a few thousand years to complete. It is these years that are really chaotic and interesting. Each magnetic period is called a chron. The latest geomagnetic reversal occured 780.000 years ago, the Brunhes–Matuyama reversal. So it is high time for a new one 🙂

What happens during a Pole Reversal?
During the reversal the magnetic field wont disappear completely, but many different magnetic poles will chaotically form in different places until it stabilizes again. Basically during this procedure the magnetic field would be much weaker, thus high energy particles normally deflected by it will bombard the Earth, cosmic ray collisions will produce lots of secondary radiation. These are yet theories though. Another theory suggests that even if the Earths Magnetic Field disappeared completely the solar winds would induce enough of a magnetic field to shield the Earths surface from these high energy particles. Either way, Magnetic reversals have been linked to Mass Extinction (although not yet confirmed), and it is a quite interesting thinking about how it would impact our lives if it suddenly started to happen.

Studies have shown that the Earths Geomagnetic Field is currently weakening, and we are heading towards a Geomagnetic Reversal, plus nearly twice the average time has passed since the last reversal, so beware,
Mete.

Further reading on Geomagnetic Reversal and the Earths Magnetic Field:
http://science.nasa.gov/science-news/science-at-nasa/2003/29dec_magneticfield/
http://www.nasa.gov/topics/earth/features/2012-poleReversal.html
http://www.lifeslittlemysteries.com/2158-earth-magnetic-field-poles-flip.html

Orbit of Earth&Moon around Sun

We all know that the moon orbits the earth. (Well actually they both orbit about their common center of mass (barycenter), which for the earth-moon system lies about 1500km inside the Earths center, so the center of mass of the Earth-Moon system is actually inside the Earth due to the Earth being much much more massive, so we can approximate and say that the moon is orbiting about the Earth). Anyway, just imagining that the Moon orbits about the Earth and then the fact that (similar mass argument for the Earth-Sun system) the Earth orbits about the Sun, what do you think the Earth-Moon orbit around the sun would look like? This is actually a very interesting and hard to visualize question. Just try it.

Will the Moon ever be going backwards around the Sun, relative to Earth, considering that it is going around the Earth, as the Earth goes around the Sun. The answer is no.
Not like this: https://haplofromnexus.files.wordpress.com/2012/11/moon_sun_wrong.jpg
Like this: https://haplofromnexus.files.wordpress.com/2012/11/moonorbitdiagram.jpg
Or even better like this: https://haplofromnexus.files.wordpress.com/2012/11/moon_synodic_cycle.jpg

There are no rearward loops in the Moons solar orbit, due the fact that the orbital velocity of the Moon about the Earth (1km/s) is small compared to the orbital velocity of the Earth about the sun (30km/s). Also because the suns gravitational pull on the moon is over twice as great as the Earths pull on it, the Moons orbit around the Sun is always convex.
Have an orbital day,
Mete.

You can read more about this topic here:
http://www.math.nus.edu.sg/aslaksen/teaching/convex.html
http://en.wikipedia.org/wiki/Orbit_of_the_Moon

Seeing round a corner (Femto-Photography)

Can you see round a corner, without using a mirror?
Well, apparently using femto-photography you can. Femto-Photography is a term describing ultra high speed imaging. And when I say ultra, I mean ULTRA. It was first used on objects by a team at the MIT Media Lab lead by Ramesh Raskar. You can watch the video below, I’ve provided a link to it (it is amazing).

Basically we watch light exit a laser and travel for one trillionth of a second and bounce around and disperse into darkness, it all looks quite great. If instead of a laser pulse it was a bullet fired from a gun we were watching at this time scale, we would be sitting watching it for 1.5 years. Light is fast, the fastest (c = 3×10^8 m/s), about a million times faster than a bullet.

Seeing around a corner is done by tracking the path differences of individual photons fired from the camera bounced off a wall to the object back to the wall then back to the camera. Because the camera is so ridiculously accurate the object in the other room is basically replicated on the screen to exact shape, to understand better watch the video by Ramesh Raskar’s team.
So basically, let there be light..
Mete.

Link to video:
http://www.youtube.com/watch?v=Y_9vd4HWlVA
Further Reading:
http://web.media.mit.edu/~raskar/trillionfps/

One trillion frames per second is truly an amazing concept…