“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.

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.

“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.


“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)

“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.

“Will we ever discover aliens?” asks Frank (9)

Frank, as my team suggested, in 2009 NASA’s Kepler telescope began pointing at a small patch of sky for four years. In that time it found a series of stars with Earth like planets surrounding them. If you multiply this little bit of the sky to cover the whole Universe you are talking about over 50 billion Earth like planets. A good assumption would be that some form of life found it’s way to existence on some of them. Maybe they have yet to develop, like us, a way of communicating over the great distances involved.

If you are a teacher read the following Guardian article Updated 26/02/2017

Shabaar (9) asked “Can humans cause an ice age?”

The last ice age ended about 11,700 years ago. It started almost 3 million years before that and was thought to have been caused by changes in the way that the Earth moved around the Sun.

So can we cause a new ice age? From this evidence it seems unlikely that we (humans) can cause a future ice age. With our production of greenhouse gases (Carbon Dioxide, Carbon Fluoride compounds and other related gases) it likely that we will be warming the atmosphere rather than making it colder. This may cause weather extremes which might make life on our planet (for humans) unacceptable. See the following link

Jessica(8) asked several great questions about the Solar System

Jessica. I have asked my team to answer the information based questions. I will try to help you with the other questions.

Jessica asked about Dwarf planets, the temperature of the Sun, The Earth’s layers and the size of Jupiter. Here are the comments from my team.



I was interested in your question about Venus having an opposite spin to that of Earth. Earth has (if you are above the North Pole) a Counter (Anti) Clockwise spin while Venus (if you are above Venus’s North Pole)has a Clockwise spin. Most of the other planets spin in the same direction as the Earth. Here is a little experiment…..

Pick up a pencil and holding it upright begin turning it in a clockwise direction,  now still turning the pencil, turn the pencil through 180 degrees. Which way is the pencil now rotating, clockwise or anti clockwise?  It is thought that close to the beginning of the Solar System a close encounter with another large object caused the axis of Venus to move through 180 degrees. Is that a theory or a hypothesis?

To your question about the position of Mercury – I have no idea why it is the nearest planet to the Sun. At the beginning of the Solar System you have the Sun surrounded by orbiting space dust. This dust slowly collects together and the planets begin to be formed. The closest ring of dust to the Sun formed the closest planet (Which we call Mercury).

‘How many volcanoes can go off at once’ is Charlotte’s (9) question

Charlotte it might be worth reminding ourselves of what is a volcano, and why do they occur. I’ll let my friends start the discussion.


Some interesting thoughts team but we have to look at Charlotte’s question.’How many volcanoes can go of at once?’ Firstly there are recorded to be 1500 volcanoes in the world as we know it. There are also lots of volcanoes under the sea but we don’t know how many. Of the 1500 about 500 have been active over the last 100 years. So Charlotte,  it is quite difficult to give you a definitive answer. For a volcano to erupt there needs to be some activity in the magma (the molten core of our Earth) and maybe the tectonic plates (the mantel plates that make up the surface of our Earth). Where the plates meet there is lots of tension, this normally causes earthquakes (New Zealand) but could allow magma to escape via a volcano.