[NakedScientist (OP)]

A new feature, starting this week is "Question of the Week".

We'll post the question initially, everyone can have a go at answering it, then we'll hit you with the answer at the end of the week, together with the new question.

Please feel free to submit appropriate questions via our contact page :

http://www.thenakedscientists.com/html/contacts.htm

Here's the first question :

"Why do we get goosebumps"

Fire away...

TNS

[Broca]

Our ancesters had much more hair than we do. In those days, when they became cold they would get goosebumps as a skin response which would raise the hairs on their body. By raising the hairs on their body the air could not circulate as easily thus creating a type of insulation. The air would be warmed by the body heat which in turn would warm them. We have less hair than those who came before us, we still have the same skin response however, and the goosebump is a raise in the skin where the hair protrudes and we can see it easier since we do not have the same amount of hair covering our bodies.

[bezoar]

Do animals get goosebumps?  Or at least primates?

Bezoar

[Broca]

Yes, animals get goosebumps as well. They get them for the same reason humans do and also animals get them to make themselves look a tad bigger when threatened. It is a survival adaptation.

[Ians Daddy]

Do we get goosebumps when frightened for the same reason?

[Broca]

I would guess yes, but am not certain. I would think it would again be an adaptaion for survival from when we were covered in hair.

[NakedScientist (OP)]

ANSWER TO LAST WEEK'S QUESTION : "WHY DO WE GET GOOSEPIMPLES / GOOSEBUMPS ?"

We have inherited this rather bizarre phenomenon from our hairier ancestors. Goosepimples, or goosebumps (as the Americans prefer to call them), are elevations in the skin at the base of hairs. They occur when a tiny muscle called a piloerector muscle (from the latin word PILUS meaning a hair) contracts to lift up the hair.

In hairier animals, making the hair stand up like this helps to trap an insulating layer of air against the skin which, in turn, cuts down heat loss and hence preserves body temperature. That's why they appear when you get cold.

The more observant among you will also have noticed that goosbumps can also appear when you are nervous or frightened. This is also the origin of the saying "feeling the hairs on the back of my neck stand up" and that's because the nerves which supply the piloerector muscles are also activated by fear. The evolutionary benefit of this is that an animal which makes its fur stand on end appears larger than it really is, and hence is more likely to scare off its opponent in a challenge situation. The situation is somewhat analogous to a puffer fish expanding when frightened.

So there you have it, the cause of goosebumps.

This week's question is below.

[NakedScientist (OP)]

THIS WEEK'S QUESTION : - Have a go - brownie points to the person who gets closest to the correct answer, which we'll post in a week's time.

"WHY IS THE SKY BLUE ?"

[cuso4]

Right this is a guess.

We see colours because objects absorb some wavelengths of light and reflect others. So a sensible guess is that the water particles in the atmosphere absorbs all the colours but blue. And the blue light reflects into our eyes that's why we see blue.

Angel

[Exodus]

Christopher, does this have something to do with good old Lord Rayleigh?

Resident Tour Operator - The Naked Scientists

[Ians Daddy]

Reflection of the ocean.

[cuso4]

Ronnie, I originally thought about this answer as well but then I questioned why the ocean has that blue colour,the colour is due light that shines on it. Deeper the ocean the darker the colour, if what you said is true why doesn't the colour of the sky become a darker blue?

Another question came to my mind, why is the sky appear orange/yellow during sunset? (or may be it's the cloud?)

Angel

[Ians Daddy]

I may have that backwards. Maybe the ocean is blue because it is reflecting the sky. It seems that I learned that it was reflection. I remember that it is due to the prysm effect. Diffused light through water droplets.

In fact, I believe you are correct, it would be the clouds that made it yellow / orange / red. Due to the angle of the sun i.e. morning / evening, and the density of the water of the clouds. I guess that when the sun is low, its refracting the light as reds and when the sun is high, it would be blue...less break up? What makes a gray sky?

[cuso4]

Air pollution?

Angel

[NakedScientist (OP)]

ANSWER TO "WHY IS THE SKY BLUE ?" :

The sky is blue due to an effect of the earth's atmosphere on the light reaching us from the sun.

Although sunlight looks 'white' it is actually made up of a whole spectrum of colours which you can see in a rainbow, or with a prism. The different coloured lights have different wavelengths ranging from blue light (which has the shortest wavelength) to red light which has the longest.

The Blue light is strongly scattered by the oxygen and nitrogen in the atmosphere, whilst the other colours, with longer wavelengths, are not affected.

This means that when light waves arrive from the sun, some of the blue light is bounced about and scattered in all directions by the air so that it no longer seems to be coming just from one place - the sun - and instead the whole sky seems blue. But the rest of the light (with longer wavelengths) passes unaffected straight through the atmosphere to your eye and hence the sun looks a yellowy red colour (white minus some of the blue).

So why does the sun go red at sunset ?

This is because as the sun 'sinks' the light has to travel further through the atmosphere to reach your eye meaning that more of the blue (and shorter wavelength light) is scattered (removed) than when the sun is high in the sky, making the sun look even more red.

TNS

[NakedScientist (OP)]

THIS WEEK'S QUESTION OF THE WEEK :

"WHY DON'T PENGUINS FEET FREEZE ?"

[noden1]

if they did you would not be able to pick up a penguin!!!

[Qing]

I guess they might have some kind of fat under the skin which will generate heat and provent from freezing. But as I said, it's only a guess and I've no idea.

Qing

[cuso4]

Penguin's feet are covered by its thick waterproof fur which can trap air and act as insulation. And I guess their feet are padded with ... probably fat which again acts as insulation

Angel

[Ians Daddy]

THIS WEEK'S QUESTION OF THE WEEK :

"WHY DON'T PENGUINS FEET FREEZE ?"

A penguin's feet are like a duck's feet, so they don't have any protective layers of hair or fat. I would guess that it would have to do with an internal thermostat. Cold / warm blooded creatures must adapt to their surroundings. Maybe it's the lack of blood that keeps their feet from freezing up. Or, maybe their pumped full of hot blood that is heated from their little fat bodies.
Being flightless, they have no alternative but to adapt. Besides, their easier to punt when they're not stuck to the ground.

Just a thought.