Why is it always better to look for shooting stars just before dawn? This shows a simulation of the Earth going on its orbit around the Sun, and encountering the debris from a comet that has passed by. This is precisely what the Earth has been doing for the past couple of days, creating the Perseid meteor shower. The A.M. half of the Earth is at the front of the orbit, and like a car’s front wind shield it picks up a lot of the debris. Have a look out for meteors again tonight! [code] [more]
This photo shows an aerial shot of some clouds forming what is called a Von Karmen Vortex street. This phenomenon is caused by the separation of different fluids when passed over a significantly blunt edge. This shot is specifically taken by the Juan Fernandez islands just off the coast of Chile.
Bubbles are just one of those things that we find fascinating, they float, they’re colourful and are incredibly satisfying when popped. The science behind them is both interesting and quite relevant to many other aspects of science.
Bubbles work best when water is mixed with soap, but why is this? What soap does is it actually reduces the surface tension of the water, despite what is commonly thought. Soap in this case is more scientifically known as a surfactant and not only reduces over all surface tension but also acts to equalize the forces around the bubble. Soap stabilizes the bubble because as the film of soapy water is stretched the localized concentration of soap actually decreases, increasing the surface tension and pulling the points back together. The spherical shape is due to the bubble wanting to have the lowest possible surface area to volume ratio.
An interesting mathematical property of bubbles is that when merging you can only get 3 bubbles to meet along lines that are 120 degrees apart and will also work to adopt the smallest possible surface area. When getting four bubbles to meet they’ll only meet at a point and take on a shape where they’re 109.5 degrees apart, the same angle adopted by tetrahedral molecules. When a large bubble and smaller bubble share a wall, the smaller bubble will also bulge into the larger bubble due to higher internal pressure in the smaller bubble.
The other fascinating thing about soap bubbles is the spectrum of colours they display. This is caused by both the random varying thickness of parts of the bubble and also by the way light passes through the bubble. Most light bounces straight off the bubble, but some passes through the film and then either passes through the other side or bounces off refracting as it goes. Light waves may bounce around inside the bubble indefinitely and this along with interactions with other light waves gives the rainbow effect.
ashifttowardlongerwavelengthsof the spectral linesemittedby a celestial objectthatis caused by the object moving away from theearth.
If you can understand that, great! But for those of us who cannot, consider the celestial bodies which make up our night sky. Did you think they were still, adamant, everlasting constants? They may seem to stick around forever, but…
Boy, you were wrong. I’ll have you know that stars are born and, at some point, they die. They move, they change. Have you heard about variable stars? Stars undergo changes, sometimes in their luminosity. (We are, indeed, made of the same stuff as stars).
So, stars move. All celestial bodies do, actually. You might have heard about some mysterious, elusive thing called dark energy. Dark energy is thought to be the force that causes the universe to expand at a growing rate. If it is proven to exist, dark energy will be able to explain why redshift occurs.
Maybe you can understand redshift by studying a visual:
These are spectral lines from an object. What do you notice is different in the unshifted, “normal” emission lines from the redshifted and blueshifted lines?
The redshifted line is observed as if everything is “shifted” a bit to the right— towards the red end of the spectrum; whereas the blueshifted line is moved to the left towards the bluer end of the spectrum.
Imagine if you were standing here on earth and some many lightyears away, a hypothetical “alien” was standing on their planet. With this image in mind, consider a galaxy in between the two of you that is moving towards the alien. You would then observe redshift (stretched out wavelength) and the alien would observe blueshift (shortened wavelength).
A simple, everyday example of this concept can be observed if you stand in front of a road. As a car (one without a silencer) drives by, the pitch you observe changes. This is known as the Doppler effect. Watch this quick youtube video titled “Example of Dopper Shift using car horn”:
(You may not be able to view it from the dashboard, only by opening this post on the actual blog page. You can watch the video by clicking this link).
Notice how as the car drives past the camera man, the sound changes drastically.
Understanding redshift is important to scientists, especially astronomers and astrophysicists. They must account for this observable difference to make the right conclusions. Redshift is one the concepts which helped scientists determine that celestial bodies are actually moving further away from us at an accelerating rate.
Glow in the dark stars are one of those staples of children who love space (Aprox. 100%) and they’re always a source of wonder. So here goes my scientific explanation for how glow in the dark materials work.
The first step in phosphorescence (The fancy term for glow in the dark) is the same as for most light-matter interactions. Light strikes the atoms and bumps an electron into a higher energy, “degenerative” orbital as some parts of the light are absorbed. However instead of falling back down to the ground state, the electron becomes trapped in the higher energy state. Molecules and compounds that display this quality are called phosphors and are also responsible for pixels in CRT screens. Eventually however the electrons do move down, although much slower than in most molecules due to a small energy barrier that can overcome by random fluctuations and as they do move down energy in the form of light is released. This means the energy that was absorbed earlier is released over a slower period of time causing the material itself to glow for several hours on end.
It should be noted this isn’t the only way things glow, certain materials glow in response to various forces such as mechanical stress (apparently pulling two parts of duct tape apart releases light) while things such as glow sticks, fire flies and the CSI fan’s favorite: luminol (which reacts with iron in blood among other things) release light because of chemical reactions, this process is called chemiluminescence.
Cosmic sink-holes or Black Holes is a region of spacetime from which nothing, not even light, can escape. The theory of general relativity predicts that a sufficiently compact mass will deform spacetime to form a black hole. Around a black hole there is a mathematically defined surface called an event horizon that marks the point of no return. It is called “black” because it absorbs all the light that hits the horizon, reflecting nothing, just like a perfect black body in thermodynamics. Quantum mechanics predicts that black holes emit radiation like a black body with a finite temperature. This temperature is inversely proportional to the mass of the black hole, making it difficult to observe this radiation for black holes of stellar mass or greater.
Although this may not be remarkable to most of you it’s something that blows my mind everytime I think about it. Right now you’re probably sitting down on a chair or something, but in reality you’re actually hovering just slightly above it. The distance itself is tiny around about 1/10000000000 of a metre or one Angstrom for those in the know. But why? Well it all has to do with our good old friend, electro-static repulsion. You see the electrons that make up you and the electrons that make up the chair have a repulsive effect, which means they can only ever come within a certain distance of each other but never touch. This effect is also the reason behind why we can’t walk through walls, despite as you may know matter being almost entirely empty space. Everything that feels solid to you is really just an illusion made by the forces between electrons.