“Why do stars twinkle” asked Mia (8)

Many thank team. I think Mia has all she needs for a little bit of experimentation.

Mia, in a darkened room , put the aluminum foil on the floor, place the bowl over it and shine the torch onto the bottom of the bowl.

What do you see?

Now add some water to the bowl(about half full). Let the water settle and then shine the torch onto the bottom of the bowl.

What do you see?

Finally, still shining the torch onto the bottom of the bowl give the water a bit of a vigorous stir with a spoon or even the end of a pencil.

What do you see?

Is what you see when the water is moving different from when it is not moving? Maybe the moving water is a bit like the moving air through which you are seeing the stars.

Tell us what you see. you can do this in the Reply box below.
(Anyone reading this post who wants to ask a question or make a comment please feel free to do so)

Liam (7) asks “What causes an earthquake?”

Thanks team. When the Earth cooled down the crust was formed over the whole planet.

However, after the crust was formed there was still a lot of activity in the molten core of the Earth. This caused cracks in the crust and it is these cracks which are the cause of Earthquakes. Scientists have investigated the cracks and created a map of where they are.

You can see these in the maps below.

The lines indicate the cracks on either side of our Earth. The spaces within these cracks are called  ‘plates’. These plates are constantly moving (very, very very slowly).

Any idea what is making them move?

Some plates are moving away from the plates next to them BUT that means they are also pushing up to other plates on the surface. It is this movement that causes the earthquake.

Where do you think the earthquake happens …is it in the middle or outside of a plate? Where is your country?

I have created two jigsaws of the Earth images above. Print them, stick them on some cardboard, and cut them out and make your own world of ‘plates’ and try moving them.

Link to Jigsaw 2

Link to Jigsaw 1

Want to ask a another question, or make a comment. Please do.
(Anyone reading this post who wants to ask a question or make a comment please feel free to do so)

“When the Sun blows up will Mercury smash into Earth?” asks Flynn and Freddie (10)

 

Below is a short video of the expansion of the Sun. Again this is a hypothesis based upon observations of our Universe.

The expansion is thought to be caused by firstly the Sun running out of fuel (it uses  Hydrogen, converting it by a fusion reaction to Helium). As the Sun cools the centre will expand, (any thoughts on what might cause this?) pushing out the rim of the Sun and consuming Mercury, Venus and The Earth and eventually it becomes a Red Dwarf. It is suggested that Mars will survive.

What is the difference between a hypothesis and a theory?

Hope this helped. Please comment or ask another question.
(Anyone reading this post who wants to ask a question or make a comment please feel free to do so)

Angus and Lachie(10) ask “Are aliens real?”


……………..I personally think that with so many potential places where life, in what ever form could have developed that aliens do exist and we have now, to wait, for contact.

Of interest is that life started developing on Earth in a very different way from how we would expect. The early bacteria were, it is thought, cyanobacteria. This bacteria ‘eats’ Nitrogen gas and exhales Oxygen and in doing so killed itself by poisoning its atmosphere. The Earths atmosphere moved from being a Nitrogen to an Oxygen atmosphere. So ………………………..this might not always happen on other Earth’s thus the type of life which humanity may meet in the future could be Nitrogen based.

The cyanobacteria do still exist in Earth’s deep oceans.

Also look at a previous post on aliens.

(Anyone reading this post who wants to ask a question or make a comment please feel free to do so)

“What was the first plant that ever grew on Earth?” asks Mahdiyat (8)

So what now? Thanks team, some good answers.

It would be great if we could do some small investigations using Moss.

1.Firstly let us confirm that the moss has no stems or flowers.

2. Secondly a more long term experiment. Try ‘planting’ your moss on a rock. Before planting look closely at the surface of the rock. compare the surface 6 months after planting (and not disturbing the Moss).

Now a story ……..

The moss was the Earth’s first plant and it took over the world. It damaged the rocks it settled on and it took all of the Carbon Dioxide out of the atmosphere. This made the Earth very very cold (the first ice age). The coldness killed most of the moss and as the Carbon Dioxide built up again it allowed other plants to share the Earth with it.

(Anyone reading this post who wants to ask a question or make a comment please feel free to do so)

“How do you measure the distance to the Sun and stars?’ asked Julian (12)

 

Julian, quite a challenging question. I will only be trying to answer the first part – the Sun-Earth distance and the Earth-Stars distance.? Even then as my team suggests, I might be introducing mathematical terms that you have not met yet, but I have included links to other sources of help.

To answer the first question I recommend you read a Universe Today article   It is an excellent historical review of the problems that the early scientists had in determining the Earth-Sun distance. The answer finally came from observations of the movement of the planet Venus across the face of the Sun. In it the writer refers to a Nasa document that tries to explain the methods used. In present times the distance to the Sun is measured by ‘bouncing’ a radar pulse of of it.

Determining the distance to the other stars becomes possible once the Earth-Sun distance was known. It uses a technique called parallax.  I would like to illustrate this with a question which tackles a simpler problem. ‘How far is my finger away from my nose?’

Try this little experiment, put a finger in an upright position in front of your nose. Now close one eye and note the position of the finger. Close that eye and open the other one. The finger moves! Now suppose, with help, you could measure the amount of movement. You could end up with diagrams like those below. Did you make a note of the position of your finger relative to your nose? No – you can now see how you could work this out.

Now let’s do a little geometry and add an axis

We can then measure the angle of the apparent movement

You end with a right angled triangle ABC, knowing the angle x AND the distance between your eyes you should be able to do a bit of trigonometry using TAN x = opposite/adjacent (Tan x = AB/BC) and work out the distance of your finger from your face. For an introduction to trigonometry please look at this site.

Amazingly this is (in a crude way) the same process by which astronomers can measure the distance to the stars. Instead of using the distance between your eyes they use the orbit of the Earth. They look at a star and make a note of it’s position and then do the same thing 6 months later when the Earth is at the opposite side of the Sun. They therefore have AB (the distance between the Sun and the Earth and they have the angle through which the star has apparently moved. 

This gives the route to determining the distance between the Earth and a Star.

 

(revised 14/05/17)

 

“If I was sucked into a black hole what would make me die?” asked James (12)

James, thank you for your question. I had a similar question from  Sheereen  click here to see my, and my friends answer.

It is thought that a ‘black hole’ is produced when a rather large star comes to the end of it’s life. It collapses in on itself and forms an object of incredibly concentrated matter. As ‘gravity’ is a property of the quantity of matter (see my answer to Ernie’s question) the collapse causes an immense increase in the gravity from the  smaller collapsed star.  

It is unlikely that our Sun would end in this way as it is classified as a smallish star. It is likely to become something called a ‘Red Dwarf’ star.

The ‘black hole’ is explained by the fact that this concentration of gravity ‘pulls’ light into it, thus the ‘hole’.

Now if you were close to the collapsed star in your spaceship you would also be pulled into it and unfortunately be added to the mass of the collapsed star. Sorry, you will be crushed.

(slightly revised 20/4/2016)

Donna (7) asks “Where do clouds come from?”

Donna, many thanks for the question. Before trying to answer it I thought I would ask my team a question.

Donna, what do you think about the puddles question? Think about how you would answer it and then go to my answer to a previous question.

Now to your question. Firstly I have created a little animation to show how the puddle disappear. You have to imagine that the shapes are water particles (molecules is the proper word). In the puddle they are all moving around. Most of them like being with the other particles BUT some are just moving around a little bit too fast and manage to escape from the puddle. When the Sun begins to warm the puddle it makes more water particles move around faster and more escape. This goes on until the puddle disappears.

 

The water particles are very small and are are lifted by the air up into the sky. High above the ground the air is quite cold so the water particles ‘slow down’. When they are moving ever so slowly if they meet another water particle they join up with each other and form droplets of water. This is how a cloud begins to form.

At home look at the steam from a kettle, BE VERY CAREFUL AND CONSULT AN ADULT.  At the exit of the kettle spout you can see nothing, BUT just above this the hot water particles begin to cool down and slow down and reform clouds of water.

(revised 21/4/17)

“If we could put asteroids around Venus, could it then be made habitable?” asks David (7)

Thanks team, I am tempted to agree with you, however there is some evidence that once upon a time millions of years ago the surface of Venus was very much like the surface of the Earth and that there might have been water on the planet. NASA has also managed to land a small spacecraft onto the surface of Venus so it might be possible, in the future to land a bigger spacecraft which could contain humans. However it is unlikely that the planet could be made habitable. Maybe Mars would be a better bet?

David, could I have your thoughts about the ‘asteroids’ in your question, It might make me change the answer to the question. You could reply by making a comment in the ‘Leave a Reply’ box below.

Why do we have droughts? asks Lisa (10)

It is a difficult question to answer. There are a lot of possible things that could cause a drought, however one of the most interesting is the effect of atmospheric pressure.

If you listen to weather forecasts you would have heard of a low and high pressure areas. You might have also noticed a pattern. When the weather forecast talks about low pressure it is normally accompanied by rain while high pressure is accompanied by sunny periods and dryness. Dryness over a long period of time could mean the loss of a lot of ground water and therefore create a drought. You get long periods of high pressure over deserts,

So why does this happen?

When you have high pressure dry air descends from the colder air higher in the atmosphere (cold air is more dense and heavier than warm air. In low pressure the movement of the air is in the opposite direction with the warmer, ground level air rising carrying with it water vapour which eventually forms clouds as it gets colder.

Lisa, there are some difficult ideas here. Think about them and then ask another question.That’s the way science works.


Revised (03/02/17)