Astronomy, science and stuff.
If Earth Had Rings
First off, they would be really pretty to look at. They would also dominate the sky in both night and day at exactly the same place as they would never rise nor set. And at night you would see the Earth’s shadow swing across the rings, like in the 4th photo here.
However, life would be very different on Earth if this were the case. Nocturnal animals would have a hard time being nocturnal, as the light reflecting from the rings would illuminate the night.
Because we are closer to the Sun than Saturn is, the rings would be more rocky than ice, making them less bright but still pretty bright. In fact, you would see far less stars at night (living anywhere other than the equator or the arctic circle) because of the light pollution and not to mention ruin most meteor showers because of that.
During the day the rings would block sunlight in certain regions of the planet creating wild weather cycles and effecting plant life as well. So basically, they would be definitely pretty to look at but they would also make a whole lot of things screwy.
Illustrations by Ron Miller // io9
— Click the photos for captions
Let’s talk about the dark night.
Yes this post is about Batman.Our common assumption is that the night sky is supposed to be dark with only few dots of light.
But then, aren’t there supposed to billions upon billions of stars in the night sky emitting light. Yes, they are very far away, but, there is nothing stopping (like air or glass) the light from reaching us. So, shouldn’t all those stars make the night sky (very) bright and not dark ?
This is actually called Olbers’ Paradox.
Let’s look at the problem in another way. We can divide the universe into a series of concentric shells, being 5 light years thick. Thus, a certain number of stars will be in the shell 1,00,000 to 1,00,005 light years away. If the universe is homogeneous at a large scale (i.e., static), then there would be four times as many stars in a second shell between 2,00,000 to 2,00,005 light years away.
But, the second shell is twice as far away, so each star in it would appear four times dimmer than the first shell (intensity is inversely proportional to the square of distance). Thus the total light received from the second shell is the same as the total light received from the first shell.
Thus, the argument is that if the universe were static and filled infinitely with stars, the night sky should be much brighter than it is now.
I think you guessed the loop hole here. I said if the universe were static, which it clearly isn’t.
The Big Bang explains this paradox by saying that the universe started at a point, and expanded from that point. Thus, it is not static.
We know that the expansion is accelerating. So, two things happen.
One is that, those stars in the night sky are moving away from us and the distance between them and us increases. This increase the time for to see them and eventually it takes millions of years for the light from those stars to reach us.
Second, which is the more important reason, is that these starts get redshifted away. Redshifting is when the wavelength of an object moving away from us goes towards the red side of the spectrum and eventually, it goes into the infra red, which we cannot see. It is like we listen to a honking truck passing by at great speed. As it moves away from us, the the sound becomes softer and softer and eventually it is inaudible.
So, because of these reasons, we never get to experience the real night sky light. But, it may be a good thing, as otherwise our eyes would be blinded by the light !
Image via Wikimedia Commons
Hydrogen Peroxide (H2O2) reacting with dish soap with Potassium Iodide as a catalyst.
It’s a pretty fun experiment to do, if you do it right. (In the first gif the girl screwed it up.)
Wild Flower under the Milky Way
“This flower is called Primula Denticulata and is located at 1500-3000m above sea level in northern part of Yunnan, China. I had strong desire to take a macro image of these flowers and it took me an hour hour to find them. Putting the camera on the slope, focusing, composition and lightning were all very difficult but the worst thing is shortness of time to moonrise. I had to leave soon.” — Jeff Dai
Amino acids chart, handy for any biochem major
I used to know all of them and draw every single one of them…
DNA prediction of categorical eye and hair colour on the individual level. Examples of applying the HIrisPlex system to four European individuals (A–D). The actual eye and hair colours are displayed on the left side by photographs. The HIrisPlex prediction results, in terms of the probabilities belonging to certain colour categories, are shown on the right side, where the colour categories with the highest probabilities are highlighted.
Human hair, eye, and skin colour are very complex and difficult to predict, because each of these traits is controlled by more than one gene. It’s not really a matter of a child taking after the father or mother’s side; genes don’t work that way. What matters is which parent has the dominant versions of the various genes that affect the traits in question, because these are the ones most likely to be expressed by the child - though not always.
Every animal (including humans) carries two copies of every gene. Scientists now estimate that a human has about 30,000 genes in his/her genome, and every human has two copies of that genome: one from mom, and one from dad. The two versions of each gene (called alleles) may be the same in a single person, or they may be different. This means that the different versions can combine and interact in unpredictable ways to produce a wide range of phenotypes (physical appearance).
A trait that is controlled by several genes is called a polygenic trait. A polygenic trait is the expression of a single phenotypic trait that is affected by the action of more than one gene. There are too many examples to list, since most traits are - at least to some degree - polygenic. But human hair, eye and skin colour are among them.
Hair colour is a result of interaction between several genes that not only control the colour of the hair pigmentation (one gene controls the expression of brown -eumelanin- pigment and a different gene controls expression of red -phaeomelanin- pigment), but also how much pigment is deposited in the hair shaft. The darker the hair, the greater the melanin deposition, but one can’t really predict how dark a baby’s hair will be, since s/he may inherit a wide variety of “darkness level” genes from both parents, and they can recombine in various ways to produce hair that ranges in colour from very light to very dark.
If a person expresses both the eumelanin (brown) and phaeomelanin (red) genes, the hair will be reddish brown. Dark to light brown hair with no trace of red occurs when only eumelanin is expressed, but in varying concentrations. Blonde hair with no trace of red occurs when there is weak eumelanin expression and no phaeomelanin. Red hair occurs when there is strong expression of phaeomelanin and weak expression of eumelanin. Not all people express both genes, but in dark-haired people that do express both, you can sometimes see a reddish sheen in the hair in certain light. But the darker eumelanin pigment often makes it difficult to see the red pigment, if it’s present.
Light colored eyes (blue, green, hazel, grey, etc.) are usually considered recessive to dark-colored eyes. But this trait is controlled by at least five different genes. There are genes that control whether or not melanin is deposited in the iris (the dominant B allele codes for brown, and the recessive b allele, coding for no melanin, will result in pale irises. These will be blue in the absence of other pigments), the amount of pigment deposited (several genes that can combine to generate eyes that are very dark, almost black to relatively light brown), as well as overlying carotenoid pigments that can change a blue iris to green, aqua, grey, or any number of variations.
And to make things even more complicated, eye colour, like hair colour, can change with age.
Still, one can predict, to some degree, whether a child will have light-colored or brown eyes. The allele coding for light eyes (i.e. lack of melanin in the iris) is recessive to the allele coding for dark eyes (i.e. melanin deposited in the iris). For a person to have light eyes, s/he must inherit two copies of the b allele (genotype bb). A person needs only one copy of the B gene to have dark (brown) eyes, so can be either BB or Bb.
Skin colour is probably the most complex of all the traits. The shade of the skin in humans may be controlled by several genes, each with several alleles, and this makes the prediction of skin tone in a baby a nearly impossible task. x
Image of the Week: Microscopic view of lung surfactantThis microscopic image of lung surfactant, a lipid-protein material that reduces surface tension in the lung and aids in proper pulmonary function, could easily be mistaken for a whimsical textile print. A recent issue of Biomedical Beat provides more information about the fanciful designs represented in the image and how they may offer insights into developing new methods for drug delivery:
Using microscopy techniques, the researchers captured a snapshot of the changes that occur (black) when surfactant molecules are stressed by carbon nanoparticles. The scientists found that if inhaled, carbon nanoparticles could influence the function of the main lipid component of surfactant. A likely gateway for nanoparticles to enter the body is through the lungs, so this and future studies may help scientists improve drug delivery methods.
Photo by University of Kansas State
