May 2013 – Page 2 – Dr. How's Science Wows

Fun Friday – Rainbow Explosions

May 10, 2013July 22, 2014nao

Wow, its Friday again, so that must mean another Fun Friday post. This week’s experiment is quick and simple… and lots of FUN….rainbow explosions – a BIG hit with all three of my children.

You probably have everything you need already in your kitchen!

You will need:

Vinegar
Bread Soda
Some different colours of food colouring
Some small spoons
Some small plastic cups (or similar)
A plate to contain it all

What you do:

Hope this is as much fun in your house as it was in ours; Let me know how you get on!

They liked it so much they had to have a rerun….love the colours, don’t you?

Nettle Pesto Recipe

May 7, 2013August 13, 2015nao

Summer is here, the temperatures are lifting and everything green is bursting forth…. including the nettles! Don’t despair though, behind the sting lies a very useful and beneficial plant! Young nettles are great as a diuretic, a natural anti-inflammatory (used for allergies, asthma, rheumatism) and to treat high blood pressure… to name but a few benefits!

Inspired by this years emerging crop we decided to make some nettle pesto; Usually when I make it I tend to throw in ingredients according to my taste preferences but for the purpose of this blog post I handled things a bit more scientifically and weighed out the ingredients. Feel free to change them at will of course, it is very much a recipe to be “personalized”!

First up…. harvest your nettles, even better if you can recruit a helper or two, this was my “helper” for the task – gloves, hat and all!

My nettle picking helper... complete with gloves! — My nettle picking helper… complete with gloves!

Wearing our nettle protecting gloves we headed out into the back garden and collected a large basin full of lovely nettles (harvesting the top two to three bracts)…

Next I removed the leaves and washed them, ending up with a colander full!

Next step was to blanch the nettle leaves, so they were added to a large pot of boiling water for two minutes then removed with a slotted spoon and added to iced water.

Then I placed all the nettles into a clean tea towel and squeeze out the water until the nettles were fairly dry

This left me with 100 g nettles, I was ready to make my pesto!

My ingredients…

Ingredients:

100 g preped nettles
50 g pinenuts
Juice and zest of one lemon
150 mls olive oil
30 g parmesan cheese
1 clove of garlic
Sea salt to taste
Pepper to taste

All that remained was to add all the ingredients together and blend, blitz or pound them to the preferred consistency.

I got about 250 g of pesto from this, nicely filling four 150 ml bottles…

Guess what we are having for dinner this evening?

Update August 2015:

I am adding this post to the #FreeFromFridays Link up, hosted this week by Dairy Free Kids. Click on the link below for lots of great Free From recipes…

Further reading:

Stinging nettle pesto recipe
Nettle pesto recipe
Latest science on Rooibos and Nettle Tea

Blue Sea Slug

May 6, 2013July 22, 2014nao

May 6th – 12th 2013

Well did you guess what this week’s creature was? For those of you who had it just on the tips of your tongue … let me put you out of your misery… its a Blue Sea Slug, also known as a sea swallow or a sea dragon!

Blue sea slugs float on their backs on the top of the sea, so the beautiful blue colours we see are actually the underside (foot) of the creature. Their backs, submerged in the water, are actually a silvery-grey colour. They are able to float due to a large sac in their stomach which they fill with air.It’s official name is a Glaucus atlanticus and it is a nudibranch (a shell less* mollusck). These little creatures usually only reach about three to four cm in size but don’t let that fool you…. they have a mean sting! The blue sea slug preys on larger toxic sea dwellers such as the Portuguese Man O’ War (Physalia physalis). It is immune to the stinging cells (nematocytes) within these creatures and is also capable of storing these deadly toxins within its own body and using them for its own defense. The more venom it accumulates the deadlier its sting!

*Nudibranches may have shells during early stages of development but are shell less when fully mature).

Fun Friday – make a periscope

May 3, 2013July 22, 2014nao

We had fun making this one… a bit fiddly at parts but worth it, the boys love their new periscope! You will need…. 2 clean empty juice/milk cartons (1 Litre) Some duct tape Scissors Pen Ruler 2 small mirrors (I got a little double mirror in a make-up set in The Two Euro Shop (for €1.50) )

What you need

What to do: First, cut the tops off the two cartons and tape them one on top of the other (taping them at the open ends)

Cut tops off

Tape together

Next mark off a square on the top side of one of the cartons with your marker (I made the square 5cm X 5cm); Cut out the square. Repeat this step on the opposite end and side of the other carton… so if the first square is on the bottom right side of your periscope cut the second square out of the top left of the periscope.

Cut a square

Now you want to fit a mirror into each end of the carton so that the reflective side of the mirror is facing you as you look in the hole and each mirror is tilted at an angle of approximately 45 degrees. The bottom mirror is tilted up at an angle of 45 degrees and the top mirror is tilted down at an angle of 45 degrees. I was lucky, my mirrors fitted the exact width of my milk cartons so I was able to place them inside, tilt them as required and then tape them in place. If your mirrors are wider than your carton then mark a line at the side of your carton, cut a slit and slide in your mirror. Repeat for the other mirror then tape into place.

You should be able to look into the bottom hole and see what is reflected through the top hole….

Now all that remains is to decorate your periscope and have some fun…. you can use it to look around things or over things, great for playing spies, which is a very popular game in this house.

Enjoy!

How does it work? The object we see is reflecting light, this light is bounced off the top mirror onto the bottom mirror which bounces the light right onto our eyes!

FEEDBACK: I love hearing from people who have tried some of these experiment so please let me know if you try this one, or even send me some photos of your finished periscope; If you have any questions just ask!

Thought of the day – All in good taste!

May 2, 2013July 21, 2014nao

I read in a magazine at the weekend about a coffee taster who has insured his tongue for the pricey sum of €13 million! Given that there are more than 9,000 taste buds on the human tongue that works out at about €1,400 per tastebud!

My thought on reading the article was… why stop there? Our tongue is not the only place in our body where taste receptors are found! Taste receptors in the Pancreas are thought to moderate insulin production in response to levels of the sugar fructose. Taste receptors found in the lungs have been shown to respond to certain bitter tasting compounds and may, in the future, play a vital role in control and prevention of asthma! Taste receptors can also be found in the nasal cavity, the intestines and the stomach!

Then there is the fact our “taste” is influenced by other factors including smell, sight and texture! Our sense of smell greatly contributes to our taste… think about how little you can taste your food when your nose is stuffed up with a cold!

Our eyes play a large part in the whole process as well. We can even be tricked into perceiving different tastes in our food or drink if they appear visually altered. An example of this is tastes reported by people drinking white wine that was been coloured to appear as red. Even the colour and appearance of the plate or cup we eat or drink from can influence how we record taste.

Maybe the professional coffee taster should re-evaluate his insurance policy… perhaps €13 million is too conservative a figure? What do you think?

…just a thought!

All in a spin – why does the earth spin

May 1, 2013July 21, 2014nao

Phew, I really need to wake up alert these days… barely had a sip of tea in me this morning when I got bombarded with lots of questions; I was glad to see that the back of the box of Kelloggs multigrain shapes has lots of fun information about the Stars, Sun, Earth and Moon! (Well done Kelloggs!) …but this lead to the question…..

…… WHY DOES THE EARTH SPIN?

photo credit: NASA Goddard Photo and Video via photopin cc

Inertia

The earth spins because of intertia…. the tendency of a body of mass to remain in it’s state of motion unless acted upon by another force. Bit of a mouth-full isn’t it? What it really means is that an object that is at rest (not moving) will stay that way unless another force or influence changes that…. a stone on the ground will stay in place unless we kick it with our foot! Likewise a moving object will stay moving unless a force acts on it to stop it! Moving objects on earth stop moving due to friction (think of stopping your bike when you pull the brakes!).

How was the Earth made?

So how does all this relate to the Earth? Well the Earth is formed from a pile of moving gas and dust created during the big bang! As these gases and particles collapsed under their own gravity they started to spin. These spinning dust clouds continues to collapse until they formed planets – such as the Earth. As the planets formed they kept spinning and, in the absence of a significant force to stop them, they continue to do so!

And that is why the Earth spins!

How fast does the Earth spin?

The Earth takes just under 24 hours to make one complete revolution – 23 hours 56 minutes and 0.4091 seconds to be exact. This is called the sidereal period (the length of time a body will make one complete orbit relative to the stars). So what is the speed of the Earth in kilometres per hour (kph)? It all depends of where you are standing! If you were standing at the North or South pole, for example, the Earth would be moving very slowly! If you were standing on the equator the speed of the earth will be moving at its fastest… that is to say, the circumference of the Earth is greatest at the equator and therefore must move faster to complete one revolution within a day! To better understand this try holding your finger on a point on a globe while you slowly spin the globe!

Now for the maths…. the circumference of the Earth at the equator is approximately 40,000 km. If we divide this by 24 (the approximate number of hours in a day) we get 1,667 kph (approx 1000 mph).

The Earth orbits the Sun at a speed of approximately 108,000 kph (67,000 mph).

Do all the planets spin?

Yes they do but not in the same direction or at the same speed. The inner planets of Solar System (Mercury, Venus, Earth and Mars) spin at a slower speed than the outer, larger planets ( Jupiter, Saturn,Uranus and Neptune). They all spin in a counter clockwise direction – as viewed from the top (or in a west to east direction), except for Venus and Uranus. The reason for this is thought to be the result of a significant collision during the formation of these planets .

What about stars?

Stars spin too. The Sun is a giant star at the centre of our solar system and it rotates on it’s axis, taking 25 days to make a complete revolution!

Image source: NASA

Further reading:

The planets (National Geographic)
Solar System Exploration (NASA)

IF YOU HAVE ANY SCIENCE OR NATURE QUESTIONS YOU WOULD LIKE ANSWERED HERE JUST ASK, I’D LOVE TO HEAR FROM YOU…. I’LL JUST MAKE SURE I’VE HAD MY CUPPA FIRST ;0)