video

[Watch] How and why do freckles appear?

[Watch] How and why do freckles appear?

nao

Another great question this week, this time sent in by seven year old Daniel, who lives in Singapore; Daniel would really like to be a scientist when he grows up, but I reckon he already is one as he loves asking questions and finding out lots of facts about science and nature. In fact, Daniel is a regular to this blog, he often is the first to work out the Mystery Creature of the month!

Daniel’s question is…

How and why do freckles appear?

Many of us have freckles, Daniel has them too, in fact he appears IN the video as the freckle model 🙂 If you would like to know a little more about freckles (I bet you do!) just watch this video below!

Freckles are pretty common, especially in people with fair complexions, but before we look at how and why they appear, let’s take a closer look at what they are?

What are freckles?

Freckles are small spots on the skin, they are usually tan or light brown in colour. Unlike moles or some birth marks, freckles are flat on our skin. They are completely natural and harmless.

We are used to seeing them on peoples’ faces but they can be found all over the body.

They often become more obvious or more abundant when we expose our skin to the sun and that gives us the first clue as to why they appear.

freckles

Natural Sun-screen

Freckles are the result of a natural colour (or pigment) called melanin produced by the body to protect the skin against the harmful rays of the Sun.

This process is called photoprotection and this is how it works…

When UV rays of light from the Sun hit our skin they  trigger certain cells in our body to make more melanin.

The cells that make the melanin are called melanocytes.

melanocytes and freckles

 

The melanin is sent to the outer layer of our skin where it absorbs these harmful UV rays, protecting the skin cells (and the cells’ DNA) from their damage.

Usually melanin is distributed evenly around the parts of the skin that are exposed to the sun, causing our skin to tan.

When melanin is distributed evenly we tan

Sometimes though the melanin clumps together in areas, forming little dark spots that we call freckles.

When melanin comes together in small areas of skin we get freckle spots

So basically, melanin is a little like our bodies’ natural sun screen… which kind of makes freckles like natural sun screen spots I guess.

Who gets freckles?

So do only fair skinned people get them? No, that’s not so. There are probably a lot more people with fair complexions with freckles, and freckles tend to be more noticeable on fair skinned people, but people with all types of skin tones can get them too.

Freckles can appear on all skin tones

Freckles can develop on all skin tones

Freckles tend to run in families, so if your parents have them there is a good chance you do too. The tendency to get freckles is genetics… and is connected to a gene called MC1R.

So remember, freckles are natural and harmless. They are just a sign that our body is taking care of us and keeping us safe.

A big thanks to Daniel for sending in this question; if you have a question you would like me to answer just leave it in the comments below or sent it to me by email (drhowsciencewows@gmail.com).

 

Are all raindrops the same size?

Are all raindrops the same size?

nao

As you know, I love receiving your questions and I am always thinking of different ways to answer them. Some you will find in my regular column in the Irish Examiner, some I answer here on the blog, in written, video and info-graphic form.

Here is something a little bit different and I am hoping to make it a regular thing, so please let me know what you think and keep those questions coming!

Are all raindrops the same size?

In order to answer this question we need to first understand how raindrops are formed. And that story starts right down here on Earth. We have lots of water in the form of rivers, lakes and seas and when this water heats up it changes into a gas, called water vapour which rises up into the air.

The sky actually has lots of bits floating around in it – like dust and smoke particles. The water vapour tends to form tiny droplets of water around these little specks of dust and smoke and these droplets come together to make clouds.

At this stage the tiny drops are light enough to stay in the sky, but, as the cloud fills up with more and more of them they tend to start to bumping off each other and as they do they join together to form bigger droplets. Eventually they get so big and heavy that they can no longer stay in the cloud and they drop down towards the Earth as rain.

A water droplet needs to be at least ½ mm in diameter before it will fall as a raindrop.

Depending on how many droplets have joined together to make that raindrop, we already have drops of different sizes falling from the clouds.

What shape doe you think the raindrops are? Teardrop shaped maybe? No, not at all! Although raindrops are usually depicted in this teardrop shape they actually start off as nice round spheres. They have lots of forces acting on them, like surface tension which acts on the surface of the drop keeping it in that nice round shape.

As the rain drops fall they experience other forces too like air pressure. As it pushes from below and above the rain drops get squished into sausage like shapes until they eventually split into a number of small drops of various sizes and these are what fall to the ground.

So, are all raindrops the same size? Definitely not!

And they are not all teardrop shaped either.

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A big thanks to Ewan for sending in this question. Remember to keep sending in your questions. You can leave them in the comments below.

I’d love to know what you think of this video, there are lots of improvements I want to make and I’d love your comments and feedback.

 

Ten science experiments you can do with a plastic bottle – Part 1

Ten science experiments you can do with a plastic bottle – Part 1

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Do you love science and want to try out some experiments yourself? Do you worry that you’ll need special equipment and expensive kits? FEAR NOT! There are so many science experiments you can do with things you have around your home RIGHT NOW! Just remember to always ask an adult’s permission. Finish drinking your water and save that bottle because we are going to share TEN amazing experiments with you… you’ll never look at a plastic bottle in the same way again!

A few months ago I promised to share ten experiments you can do with a simple plastic bottle. If you have been following me on Face Book you will have noticed that I have shared one every week and we reached ten no problem; I’ve compiled all the instruction videos here so that you can pick and choose which ones you want to do (or, even better, try all ten).

The reason I started this was because I was sick of seeing science experiment kits full of rubbish (I am not saying all science kits are rubbish, but I have seen my fair share lately). I wanted to show you that you can do plenty of science experiments from things you have around your own home. And what better example to use than a simple, humble, plastic bottle. A great example of reusing and recycling.

PLEASE NOTE: ALL THESE EXPERIMENTS REQUIRE ADULT SUPERVISION!

Without further ado… here are first five Science Experiments you can do with a plastic bottle:

  1. make a fire extinguisher

 

2. Inflate a balloon

 

 

3. The Sneezing Alien Experiment

 

4. and 5. Ocean in a bottle experiment and Lava Lamp experiment

 

Those are the first five experiments. Have lots of fun with them, check back next week for the next five experiments. Remember to keep those bottles!

As always, we love to get comments and feedback so do let us know if you try some of these experiments; we’d love to know how you get on, did you make some of your own modifications and improvements to the experiments? Would you like us to share more video experiments?