Charlie (10) asked “How many people live on earth”

Charlie ….. a simple answer …about 7.6 billion people.  That is a big big number 7, 600,000,000. A lot of people and it all started about 2.5 million (2,500,000) years ago.

The people then where very  olde worlde and didn’t look very much like us today. They were wanderers and spent a lot of time hunting and gathering food.

This species ( a word to describe a group of animals that are alike) was  the homo species and we are derived from the homo sapien group. There were then quite a lot of different homo people, however we were the only group to survive.

Below is a drawing of the what the homo family might have looked like. Can you find the homo sapien?

What happens to your eyes when you die? asks Olivia (12)

You did suggest Olivia that the eyeball might explode when a person died.  This is very unlikely. Look at the eye image below and try to identify the muscles in the eye. they will be attached to the two things that are constantly changing in the eye.

There are muscles attached to the lens and the iris.

When you die, your muscles relax. This causes the iris muscle contracts when this happens the eye is said to dilate ….like the image below

This is probably what your eye would look like  when you are asleep. Thanks for the question.

Ronan (10) asks “How do stars form?”

Ronan ..this is my thinking about your excellent question.

Yes it is all about Gravity – There was a previous question by Tegan on Gravity. Have a look at it.

It is thought (it is therefore a hypothesis – an unproven idea)  that dust and hydrogen gas from the ‘Big Bang’ was gravitationally attracted to each other.

As the mass of the dust and gas got bigger it’s gravitational pull got bigger and the more dust and gas it attracted.

Eventually  the compact squashed ball of dust and gas started to heat up. It got hotter as it got bigger and eventually the particles of dust and gas began to break up in this hot environment and the hydrogen particles began to come together to make new particles … an atomic FUSION reaction began to occur and the star was born.

What does a dead star turn into? asks Liam (9)

Liam. Science is an interesting area of knowledge. It is recognised that it originates from an area of study called Philosophy. Philosophy (an Ancient Greek term) is about asking questions and for Science it is about asking questions about the physical and biological world. We ask the question and try to find the answers. For your question the answers are not easily found.

To try to answer your question, we have to know a little bit about the Sun. We know that in it’s centre there is an atomic reaction going on. It is not the type of atomic reaction we have in our Atomic Power Stations where we have an atomic ‘fission’ reaction occuring.

‘Fission’ means splitting something into two or more parts. The animation below shows a small atomic particle called a ‘neutron’  hitting a much bigger particle called an ‘atom’ . It splits forming more neutrons that hit other atoms, which break and form more neutrons………and on and on. This is a fission reaction and a lot of energy is released.

In the Sun the opposite is happening. Instead of fission we have fusion , the joining up of particles (Hydrogen atoms) to give Helium which creates lots and lots of energy. See the diagram below.

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Why would the Sun die? The main reason is that it runs out of Hydrogen. So what will happen then?  Firstly the Sun will get brighter. This will happen because of the helium that is produced. It will be pulled into the centre and begin to burn, adding more light and heat to the Sun’s radiation. Then as the hydrogen gets less and less the Sun will get cooler but at the same time begin to expand. It will become a Red Giant.

It is reckoned that it will expand so much that it will consume the Earth……that will happen in about 4 billion years time, however life on Earth will no longer exist in 1 billion years. This is because of the brightening of the Sun and the rising temperature of The Earth’s atmosphere, all the oceans will disappear and plant life will not be able to survive.

 

 

 

Liam Astra asks “Why does Mentos lollies make coke spurt everywhere?”

Liam, thanks for the question. Are you sure that you wanted to talk about Mentos lollies? I couldn’t find any mention of them …..only sweets …so I have focussed on them. 

Let me start my answer by showing you my favourite clip of the Mentos/Diet Coke reaction.

My first question is ….is there anything special about diet coke and the Mint Mentos tablet?

Firstly there is evidence (somebody has done some experiments) that diet coke contains more carbon dioxide gas than ordinary coke. When they make coke they add carbon dioxide gas to it. Lots of gases are absorbed by liquids. Oxygen gas is absorbed by water…..this allows fish to breathe. The manufacturers add carbon dioxide to the coke because it enhances (makes better) the taste of the coke. Carbon dioxide, like oxygen is a safe gas  – it is the gas that you and I breathe out – it is created by our bodies.

Experiment 1.  Add a Mentos to a bottle of Coke and one to a bottle of Diet Coke….is the reaction the same? Make sure that it is a fair experiment (talk with others about how you can make it fair). Make sure that it is a safe (if you have them wear goggles) and a tidy experiment. (think about your parents or teachers)

Experiment 2. Now let’s look at the Mentos tablet. Is the tablet smooth or rough to the touch? Try and find something (maybe an adult can find you a little bit of sandpaper) that will change the surface of one of the Mentos tablets (more rough or more smooth) and drop it into a diet coke bottle. What happens? Do the rough and smooth tablets both give exactly the same ‘spurt’?

You could also carry out this experiment with Fruit and Mint Mentos tablets?

Here are some magnified photographs of the surface of a Mentos tablet.

 

So what have we found out? What has roughness to do with surface area? Why does the dissolved gas decide to come out of solution when it meets the tablet?

Let me know your thoughts in the box below.

Viper Astra (9) asks “What makes earthquakes happen?”

Viper, to answer your question it might be useful if we go back to the beginning. By the beginning I mean 4.6 billion years ago when the planet was first formed. Then it was a ball of molten lava. (1 billion is 1,000,000,000 or one thousand, million)

Over the next billion years the planet cooled and bits of crust formed on its surface. We call these bits of crust tectonic plates (the word ‘tectonic’ comes from the ancient Greek word for ‘building’ ……the crust is ‘building a surface’). These bits of crust got bigger, sometimes sunk into the molten sea they were floating on, but slowly covered the Earth.

Because they floated, the ‘plates’ of crust would have constantly experienced the movement of the molten ‘sea’ below them, so they moved and bumped into each other, and they are still doing that today. It is the movement and the, bumping into each other that causes earthquakes.

Watch this short video. It explains the different types of earthquake that can occur.

Thanks for the question Viper. Not sure about something then ask another question.

What natural phenomenon made the Mariana Trench? asks Sabine (9)

The Mariana Trench ….. I have been thinking about this and I think, worked out a way of explaining the answer to your question.

Firstly

Our planet, the Earth, is an interesting planet. It has a solid surface (we call the crust) that surrounds a molten (liquid) inside, called the mantle. Like a boat on water the surface floats on the molten liquid interior. Look at the image below:

Many millions of years ago the planet was just a hot molten sphere. Slowly the crust began to form. It didn’t all form at the same time so it became a little like a cracked egg shell with each bit floating and moving on the molten mantle. These pieces were the tectonic plates. The image below shows you the present positions of the tectonic plates.

You might be able to see what tectonic plate you are living on.

These plates are constantly moving (very, very slowly). When they bump into each other they can cause lots of problems, like earthquakes. The Philippine Plate and the Pacific Plate bumped into each other many millions of years ago  and this made the Philippine Plate sink below the bigger Pacific Plate …. and the result the Mariana Trench. See the diagram below.

Where is the Mariana Trench?

I hope this makes sense Sabine. Feel free to ask another question.

Will (8) asks “What makes seeds grow?”

 

Will, thank you for your question. Let’s start with some interesting questions. Answers to these might help in answering your question. Firstly is a fruit a seed?  If it is not a seed then what is it for? Does it help the seed grow? How will we know if the seed is growing? What does a seed need to grow? Does it need soil? Do seeds grow when it is cold? Do different seeds grow at different speeds? What do you think? Are there any more questions? Remember questions are what science is all about. By investigating questions you are building knowledge of the world around you.

So, let’s think about how we could investigate some of these questions. Shall we look at just one type of seed, or choose a variety of different seeds to investigate? Maybe looking at one type of seed would help us begin to answer some of the questions. We could then look at another type of seed and compare the results. Maybe one seed would grow faster than the other?

Now we have to think about the conditions for our growing experiment ….. soil/no soil, wet/dry, light/no light, hot/cold. Even for our selected seed this can be very complicated. Can you see why?

The investigation equipment could probably be obtained at home. A empty plastic bottle, with the top cut off, would be a good holder for the seed. Some cotton wool could act as soil. A cupboard and a refrigerator could also help you create the right environment.

Let me know how it went?

Yet more questions on Space and the Solar System from William, Kylan, German, Rob, Aidan, Gavin, Lucas, Jake, Thomas and Kylie.

Hello, yet more interesting questions. Many thanks. It is brilliant that you continue to ask questions. By doing so you maybe think that you are showing your ignorance, and you are. However it is important that you do show your ignorance because that is the way that knowledge and science develop. Scientists are constantly saying “I do not know how that happens” then “I will try to find out why it happens”. My answers to your excellent questions below might therefore not be direct answers but may be directed to helping you to find the answer yourself. You can be the scientist. Here we go …..

William asked “How many stars are there in space not including the Sun and what is the hottest planet in the solar system?”

William, the difficulty I have with this question is what do you mean by Space? Space is endless so for an investigation it is better to start with a smaller known area …such as our Galaxy, the Milky Way. Even then the answer is only an estimate ….about 1000,000,000 (a billion stars) and apparently it has been estimated that there are over 1000,000,000 Galaxies in Space.

Maybe the second part of your question has an easier route to an answer. Initially one might have thought that Mercury would have been hottest – it is the closest planet to the Sun! But I am wrong, Venus is the hottest, because of its atmosphere. Why do you think this is?

Kylan asked “Is Space endless?”

Kylan, the answer to this is YES. To us humans this must be a difficult thing to grasp. We are constantly living within confined areas. To think of something as endless is difficult to comprehend.
Kylan, a great but disturbing question.

German asked “Como se origino el universo?”

German, another difficult question. You are obviously in a group who specialise in asking difficult questions. That is brilliant, because that is what science is about, asking difficult questions. There is evidence that the Universe began some 14.8 billion years ago, the Big Bang. This evidence apparently comes from a something called CMB (Cosmic Microwave Background). I think I will leave it there. I have no doubt that the Big Bang idea will at sometime in the future be challenged. Another thing about science is that scientists are always trying to falsify other scientist’s theories (prove them wrong).

Rob asked “Why no one can go to the Mars?”

We will get there Rob. When I was at the Kennedy Space Centre there was a lot of talk about the proposed trip to Mars. They are even now investigating how astronauts can live in a small self contained environment for a number of years. We have got to the Moon, which is 384,000 km away, for Mars we will have to a travel a minimum distance of 54,600,000 km. Why do I say ‘minimum’ distance for the Mars trip and not the same for the Moon trip?

I think it may happen in your lifetime.

Aidan asks “Why doesn’t NASA use a Saturn V rocket to go to Mars?”

They have a Saturn V rocket at the Kennedy Space Centre. It is massive. However they will need a more powerful (notice I don’t say bigger) rocket to launch a Mars probe which includes astronauts. The living module will have to be a good deal bigger than that used to get to the Moon and back.What do you think will be necessary for the astronauts survival?

An image of the engines of the Saturn 5 rocket  at the Kennedy Space Centre

 

Gavin asked “How does the Solar System work?”

Gavin, great question. I have already answered a similar question in a previous post. This was my answer to Rishi:

I immediately think of why does it work in the way it does? The centre of the Solar System is the Sun. The Sun is one of a group of stellar objects called stars. Our star was named, by somebody, in the past, as the Sun. Our star (the Sun) seemed to have attracted to it some massive lumps of matter/material which we call planets (planets are the biggest ‘lumps’ , the smaller ‘lumps’ are called asteroids and meteorites.

What has given the Sun the ability to attract these ‘lumps’?

You then have the amazing thing that these lumps move around the Sun. They are attracted to the Sun but do not fall into it. They rotate around it, why do they do that? . Or does the Sun rotate around them?

Lucas asks “How big is our solar system and do humans know if there are other solar systems?”

Lucas, NASA has a project called Keppler that is looking at other planetary systems. Below is an image of the space telescope that is doing this work. Note that our planetary system is the only one called the Solar System. All others are called planetary systems. The Kepler telescope has identified a number of other planetary systems and some of them are very strange. One system has two stars. Quite a few have Earth like planets. I wonder what it would be like living on a planet with two stars?

Jake asks “Will Mercury crash into the Sun in a million years?”

Jake, it is unlikely that Mercury will crash into the Sun. It is thought that as the Sun gets older, it is now about 4 million years old, it will begin to expand  and eventually destroy Mercury and Venus and the Earth. It is reckoned that this is likely to occur in 4.5 million years time.

Thomas asks “How does the Sun create radiation?”

Thomas, how many types of radiation do you know about? There is visible light radiation,  ultraviolet light radiation, and infrared radiation.  However, there is another type of radiation which produces all of these types of radiation.

The Sun’s radiation is created by a nuclear fusion reaction in its core. This nuclear reaction produces very high energy gamma radiation which, as it passes from the inside of the Sun to the outside, is converted to the other types of radiation listed above.

Kylie asks “Why does Saturn have rings?”

Great question Kylie. Saturn is one of the largest planets in our Solar System. It therefore has a great gravitational attractive force. It has 60 Moons! It is thought that the rings have been created by this gravitational force attracting lots of the bits and pieces that each year enter our Solar System. Bits and pieces like asteroids and meteorites. Gravity is an important feature of our Solar System. Have you any questions about Gravity? I would like to hear them.

Some Questions about the Solar System by Rishi, Ned, Maya, Thomas, Jackson, Adam and Pug.

Many thanks for the questions, and they are all about the Solar System. Amazingly I have just (three days ago) visited the Kennedy Space Centre in Orlando so they come at a time when I am excited by the science associated with space and space travel. I had questions before my visit and after it I had more. That’s the brilliance of these exhibitions, they raise questions. So let’s look at yours.

Rishi asked “How does the solar system work?”

I immediately think of why does it work in the way it does? The centre of the Solar System is the Sun. The Sun is one of a group of stellar objects called stars. Our star was named, by somebody, in the past, as the Sun.  Our star (the Sun) seemed to have attracted to it some massive lumps of matter/material which we call planets (planets are the biggest ‘lumps’ , the smaller ‘lumps’ are called asteroids and meteorites. What has given the Sun the ability to attract these ‘lumps’?

You then have the amazing thing that these lumps move around the Sun. They are attracted to the Sun but do not fall into it. They rotate around it, why do they do that? . Or does the Sun rotate around them?

So Rishi, your question is a great science question. From it lot’s of other questions arise, and that is what science is really about.

Ned asked “If the world split in half, would there still be a gravitational pull?”

Ned, thanks for the question. Gravity is one of those strange things called ‘forces’. Most forces are easy to define. You push things, you pull things by physically applying a force. Magnets  can push and pull so they can apply a force. So how can you explain the fact that things are somehow ‘pulled ‘ towards the Earth?  This seems to be something called a gravitational force. It’s strange. Nothing seems to be pulling or pushing you. Scientists have created a word called ‘gravity’ which describes the process of one object (of a big mass) pulling towards it a smaller mass.

We know that there is this force called gravity that exists. I am not sure that we have yet found out what causes it. We know that a very big object (of great mass) will attract a much smaller object (of smaller mass), however we have no idea why.

So at last to your question. My hypothesis (find out what that means). Slitting the world in half would mean that both halves of the Earth would move closer to the Sun because, the Sun is the biggest object in our Solar System.

Maya asked “What is the milky way?”

Maya, it’s a good question. I wonder who first used the name ‘the milky way’ and why? I firstly think about stars in the night sky, they produce white light (I wonder why – why not red or yellow light?). Does our star (the Sun) produce white or yellow light?

It is for a lot of us to really observe the night sky in all its glory. Why? It seems to be all the background light that we are experiencing when we look at the night sky. Go to a very dark place, away from the city, away from a near town and look at the night sky. You will see things you have never seen before. It is magical. You will see more stars than you have ever seen in your life. Only then will you see the Milky Way and only then will you know what it means.

Thomas asked “How many Suns are there in the universe”?

Thomas, thanks for the question. My first question is . What do you mean as Universe? As yet the investigation of the Universe in which we live is incomplete. We do not know how big it is. We do know, that the Universe consists of groups of stars that we have called Galaxies. We are in a Galaxy called the Milky Way (see Maya’s question). There are millions of stars in our Galaxy. So Thomas, in answer to your question ….we do not know …but the important thing is that you asked the question. By asking the question the quest and research for an answer continues. That is science.

Jackson asked “How big is Jupiter?

Jackson, a great question. It raised a question which I tried to find the answer to “Why do we want to know the size of Jupiter?’ I suspect it is to try to answer an even bigger question linked to Risha’s question. Why do the planets orbit the Sun? Is there some reason in there order of orbit …Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune?   Jupiter is the biggest planet in terms of mass and size in our Solar System . It would be nice if the size and mass of the planets and their orbital position was a straightforward order …but not so. That seems to be the outline of another question.

Adam asked  “How old is the Sun”

Adam, an interesting question, thanks.  It is thought that the Sun is 4.6 billion years old that is …would you believe it 4,600,000,000 years. Scientists reckon it was formed by the sudden compression of hydrogen and helium gas caused by the explosion of nearby star. Wow. This leads to lots of other questions …..think about them and let me know. The scientists also reckon that the Sun is about halfway through it’s life.

Pug asked “If all planets crashed into each other would it affect other Solar Systems?”

Pug, a good question. What do you think would happen if all the planets crashed into each other? How would it happen? Here is ia hypothesis. The most likely scenario would be the outer planets moving into a lower orbit and crashing into the lower orbit planets. They would then be affected by the gravitational pull of the Sun. They might then crash into the Sun. The Sun may therefore gain more energy and explode into a supernova. Pug, a hypothesis is an idea, can you come up with an alternative one? Let me know.