Slashdot Mirror
Parents Baffled By Science Questions
Pickens writes "The BBC reports that four out of five parents living in the UK have been stumped by a science question posed by their children with the top three most-asked questions: 'Where do babies come from?', 'What makes a rainbow?' and 'Why is the sky blue?'. The survey was carried out to mark the launch of a new website by the Department for Business, Innovation and Skills called Science: So what? So everything."
The sky is not blue due to refraction. It is blue due to Rayleigh scattering, which increases as the wavelength decreases.
My mum just left a copy of the book Where Did I Come From? on the bottom shelf in the living room. I used to love that book (and the sequel "What's Happening to Me", about puberty) when I was a little kid - the pictures are adorable and it's pitched at a good level.
My understanding is that it's density differences. Light bends when it goes from air to water, for example, because of the difference in density. Now air has small density variations. For the short-wavelength blue light, it is going through air whose density is continually changing. So it's path goes all over the place. But for the red light, with almost twice the wavelength, the density changes are lot more averaged (since it's bigger), so it doesn't see the density changes so much, so pretty much goes in a straight line.
Your understanding is - sorry - entirely wrong. The wikipedia article actually does a more or less decent job at explaining it: http://en.wikipedia.org/wiki/Rayleigh_scattering
The basic thing: Light scatters off the molecules of the air (no density variations needed). The higher the lights frequency (i.e. the bluer it is), the more it scatters.
So we see lots of scattered blue from all directions, but a lot less of scattered red, yellow, green, etc.
And because the atmosphere isn't thick enough to scatter a large amount of the colours on the red end of the spectrum, those come through more or less unscattered.
At dusk or at dawn, the light you see travels much longer distance in the atmosphere, and other colours scatter too. That's the main reason why sunrises and
sunsets are red - that's the only colour making it through.
Crikey, what a good show that was. Every single thing was personified in the cartoon - from corpuscles to neuro-electric transmissions to individual nucleotides producing proteins - and I learned more about human biology from that show than I did from 5 years of GCSE Biology (and the show was only on at about 6.30am every Sunday in the UK, about 20 years ago).
Unfortunately I don't think it's been on TV for some time now, and I can't find it on DVD anywhere. If any of you out there are parents who want your kids to understand a little bit of biology, you can't do better than to show them this.
Meta will eat itself
It's not really refraction. There actually is a refraction effect which is why we can see the sun at sunrise before it would be strictly visible over the horizon, and still see it at sunset after it's gone below the horizon. It's really more of a reflection -- think of light being scattered around by glitter except on a much smaller scale.
Rayleigh scattering preferentially scatters shorter (bluer) wavelengths more strongly. When the sun is directly overhead, as in midday, light nearer to the reddish end of the spectrum will reach you directly while only the bluer wavelengths will have been scattered. The blue that you see is light from the sun that has been scattered towards you by the air molecules in the atmosphere. The opposite happens at sunrise and sunset to make it appear red; the light reaching you has a much longer optical path to go through so nearly all of the the blue wavelengths have been scattered away leaving only the reddish light to reach you.
There's also a minor effect due to Mie's scattering off the dust and other particulates in the atmosphere. Mie's scattering deals with scattering by slightly larger particles than Rayleigh scattering.
How come I don't learn English in school even though it's my country's official language ?
If you are talking about the US, it has no official language.
Tesla was a genius. Edison however was a overrated hack who liked to torture puppies.
They need to do way instain mother> who kill thier babbys. becuse these babby cant frigth back it was on the news this mroing a mother in ar who had kill her three kids . they are taking the three babby back to new york too lady to rest my pary are with the father who lost his chrilden ; i am truley sorry for your lots
Like seriously? Stumped by the question where babies come from? Maybe these parents should read slashdot because I'm sure 90% of us can answer all of these questions, although maybe that's too optimistic nowadays.
I am a test designer.
What you are describing is what happens to every test anyone ever writes with the best of intentions. We make a test to, say, place students into the right level of language classes, and the department starts using their gain scores for their grades in those classes, muddling placement and outcome--two different testing situations that would need different methods.
Administration wants an instrument that matches the curriculum closer; you make it; they demand to know why it doesn't have X, Y, or Z. You point out that it isn't in the curriculum. They say "It should be!"
It happens every time. Even BMI, which was basically designed to find starving people, has been repurposed to define physical fitness--something it is not designed to do and cannot accurately assess.
People always misuse measures and then blame the person(s) who made them.
Welcome to my world.