.

.

This week's questions and their answers are listed here on this page
You can also view past transcripts...

• Week 1: NZ Space Expert, Anne-Marie Robinson.
• Week 2: NASA Astronaut, Colonel Jerry L. Ross
• Week 3: NASA Astronaut, Lietenant Colonel William G. Gregory
• Week 4: NASA Astronaut, Dr Shannon Lucid
• Week 5: NASA Astronaut, Dr Shannon Lucid

Week 6: Auckland Observatory education officer, John Dunlop

1. Tom Davies, Birkenhead School

Where do comets come from?

Nobody is exactly sure. The theory is that this giant cloud of comets sits way, way out past Pluto. They are sitting in something like a big deep freezer moving slowly around the Sun. Now and again one may fall towards the Sun and as it gets nearer it starts to melt and we can see them from the Earth in the Sun’s light. If you want to look it up in a book, look under ORRT Cloud as this theory is named after a Dutchman.

How do you count the stars in a galaxy?

This is a difficult one. Basically you can work out how heavy something is, say the Sun, by timing how long it takes us to go round it and how far away we are. So you do the same thing for the galaxy; you work out how long the stars are taking to get to go around the galaxy. Then you work out how heavy the galaxy is. It doesn’t actually tell you how many stars there are in the galaxy, but we imagine that they are all about the same size at the front. If you know how heavy the galaxy is then you work out roughly how many stars there are. It’s very complicated but it can be done. They reckon there are 1 – 2 billion stars in ours.

3. Zoe Matthews, Kaitao Intermediate School

Do you think that there is another planet that exists beyond Pluto?

Most modern astronomers don’t think there are any big things out past Pluto. There are lots of little things like comets, but no other planets. Sorry!

4. Matthew Dale, Karori West Normal School

How hot is the sun?

It’s about 20 times as hot as your oven. On the outside it’s about 6,000 degrees and on the inside it is almost too hot to imagine – it’s 15 million degrees approximately – but no-one has ever been in the middle to check it out. The inside of the Earth is almost as hot as the outside of the Sun.

5. Thomas Platts, Matiere School

What is the Milky Way?

Good question. If you live in a nice dark place like Nelson, you can see this big milky patch if you look out to the sky. That is what most people call the Milky Way. But it is actually our galaxy. All the stars that you can see at night is part of our Milky Way and everything else in the universe is too far away unless you know exactly where to look. It’s a giant cloud of a couple of billion stars and lots of dust and gas as well.

6. Russell Powell, Birkenhead School

If one of the planets exploded would it change the Earth’s position in the Solar System?

Good question. Basically it wouldn’t make any difference at all unless one of the chunks of the explosion hit us. Right now the Earth is going around the Sun on a bit of a lean and we think it is on a bit of a lean because it had this big collision with something billions of years which knocked it over a bit.

7. Andrew, Karori West School

How do you choose the names of the constellations of the stars?

The names have come through from the Arabs and Greeks from many years ago who made up all these stories about the stars. They drew join the dot puzzles up in the sky. Nowadays some of these names are official, such as Southern Cross and Orion the Hunter. If you come from other parts of the world the names can be different. Maori people see the Scorpius constellation as a Maori fish-hook and some see the Southern Cross as an anchor for a big canoe. So it depends where you are and which constellations you use.

8. Davon Jovanovic, Kaitao Intermediate School

What is the greatest distance that you can view from a telescope?

I’ve got a telescope and if I take it out on a really dark sky sometimes I can see a galaxy which is about 50 million light years away. That means that the light has been travelling for 50 million years and it goes about 9 million million kilometers in a year. The Hubbell space telescope which is up in space going round the Earth where is no air out there to spoil the view – that’s taken a picture of galaxies and we reckon that the light has taken about 12 billion light years to get to the telescope. You can see these pictures on the Internet.

9. Sophie Lindsay, Karori West Normal School

Why is Mars no longer a green planet like the Earth?

There is a big mystery about the water on Mars. There has obviously been all these big rivers and floods, millions of years ago, because there are all these big craters where the water used to be. Nobody is actually sure why the water stopped flowing and what happened. Because Mars doesn’t have as much gravity as us, maybe the water leaked out into space.

10. Alex Connolly, Matiere School

How many constellations are in our galaxy?

Well, I talked before about the official ones, there are about 88 of these. But really our galaxy is much, much bigger than what we can see and we don’t have shapes for all the star patterns in our galaxy because we can’t even see them all. Also, if you were to sit in one little spot in the galaxy, then you moved across to another spot, you would see the star you were looking at in the original spot as being a different shape.

11. Tom Allen, Birkenhead School

Is there any possibility that the Earth could collide with an asteroid?

Oh definitely. There have been lots of asteroid collisions in the past. If you go out into the Australian desert you will see big hug craters. In America, in Arizona, there is the meteor crater - a giant big hole in the ground. These hit thousands of years ago, but there is nothing recent. It’s likely that one will hit in millions of years to come, but I doubt we will see anything like that in our lifetime. There are people using space watch telescopes, who are tracking this, and there are some New Zealand experts who are working from Mount John and they take photos of the sky. There are a couple of hundred asteroids which cross the sky now and again. The chance of them hitting us is very, very small.

12. Kaitao Intermediate

How big is the Sun?

Basically it is a million times bigger than the Earth. The Earth is roughly about 12,000 kilometers from one side to the other. But the Sun is 1,400,000 kilometers from one side to the other.

13. Catherine Gutwein, Kaitao Intermediate School

What was the reason for having the observatory where it is?

Auckland is a big city with lots of lights and things. People would look around for a park, which was nice and dark, but not too far away from the city for people to visit. So they decided to have it in One Tree Hill because it was a big park and there weren’t any main lights. Now of course there are heaps more lights around the observatory and people would like to see it moved out into the country!

14. Andrew Palmer, Karori West Normal School

Why has Jupiter got so much gas on it?

There are no rocks on Jupiter, it is all gas except for some solid bits right in the middle which you would never find! When the Sun first started up millions of years ago it got really hot and all the radiation blasted all the light stuff out from the sun. The gases ended up in a ball around the outside and this ball collected all the other gasses and made Jupiter and Saturn. Don’t forget Uranus and Neptune are also full of gas as well.

15. Claire Luscombe, Matiere School

Which planets can you see at what times of the year?

Well, planets don’t have the same years as we do, so it’s not like in January you can see Venus, as it takes each planet a different time to go around. It takes us a year to go round, yet it takes Mars two years. In my computer at the moment it tells me that tonight if you look next to Scorpius , you will see Mercury and an orange thing called Mars. If you have a telescope you can see Neptune and Uranus if you know where to look. Jupiter can be seen which looks like a very bright star and Saturn look like a yellow star. So you can see a few planets tonight.

16. Alex Merenda, Birkenhead School

Is there likely to be another "big bang" in the galaxy or universe?

It’s a difficult one and to be honest no-one really knows the answer. People still don’t know what happened at the start of the big bang. We don’t really know if the universe is slowing down or not and no-one one can say. The whole universe is expanding. Imagine you have a big black balloon with all these stickers on it (which are the galaxies in their clumps). You are blowing up the balloon and all the galaxies are getting further and further away from each other.

17. Tom, Birkenhead School

Can you tell how old a star is when looking through a telescope? If so, how?

The age of a star depends on how big it was when it started. Young stars are hot and blue. Old ones are cooler and red. There are a couple of old ones in the galaxy if you look. We have special equipment which filters the light from the stars to the colour of the rainbow. We can tell how old a star is by which colours are missing.

18. Phillipa Hicky, Kaitao Intermediate School

Why are planets round?

Why are balloons round? When you blow it up all the force in the rubber forces it into a round shape. You couldn’t imagine it being square. It is like that with gravity. The force of gravity would flatten down anything that stood up too much and that is why the Earth is curved.

19. Andrew Goddard, Karori West Normal School

How did people find out that there was more space than we can see with the naked eye?

Nobody knows for sure. The first person to see more was probably Galilleo who lived in Italy years ago. He was the frost person to see and write about it all.

20. Carl Carmichael, Matiere School

What is happening when you see a falling star in the sky?

It is a bit of space junk. The Earth is whizzing around the Sun and it has to go right round in a year. We are travelling at about 30km per second! Because we are going so fast if we run into any left over bits of comets and we run into them. When a bit of rock hits our air it burns up into dust and all the time space dust is weighing down on us and that’s what you see. Sometimes heavier ones don’t burn up and land on Earth and you may find one on the ground.