But don’t worry, we won’t be around. 

4.- What would happen if water ends? by Paula 

We are losing water and atmosphere every day, is part of the cycle of water and the atmospheric cycle.  Some of the two elements that form the water, oxygen and hydrogen are lost in space every day, with other elements like nitrogen, neon, argon... 

The point is that the earth is an active world, and from the inner layers of our planet, with the volcanism and the tectonic plates’ movement there’s a lot of water and gases expelled to the atmosphere as well…so it remains stable (more or less). 

First: water will not end, unless we send it away from the earth. This is exactly what happened in Venus. The sun’s radiation didn’t allow to the particles of oxygen and hydrogen to get together (basically) and there’s almost no water there but a lot of carbon dioxide and sulfuric acid, because of the chemistry that forms this elements…and not the water. 

So, there’s no water there to lubricate tectonic plates, to form water clouds and cool down the planet’s surface and because of that Venus is not habitable. Here on the Earth we don’t have this kind of problem, and the water we have is going to remain with us. 

Another question is where all this water came from. This is unknown nowadays.    

5.- Could Mars crash with the Earth? by Elías 

No, it can’t. We move faster than Mars, so both planets are in different places of the Solar System. The only way that we can crash is spinning up the rotation of Mars or slowing down our one. With this, our momentum or centrifugal force will be the same and…crash! 

But this is technically impossible with the objects that we have today in the Solar System. Don’t worry; we are safe with this one. 

It turns out that a long time ago (about four thousand million years ago) they were more planets and objects around the Solar System than now, and they crash between them letting the planets that we know today as survivors of this age, called the “Age of heavy bombardment”. So, the planets today are basically stable and their orbits are not going to collide between them. 

6.- How can astronauts sleep in the space? by Valentina 

The astronauts have around 16 sets and dawns every 24 hours, so to know “what time is it” they don’t have to watch the sun’s position in the sky, because that’s useless. 

They have schedules with the hours of work, rest and sleep…and they use the hour of London (GMT) as the normal hour to work and live with.  

They sleep in sleeping bags and with blindfolds. It doesn’t matter what way you are sleeping at, because in microgravity you are floating. They normally attach the sleeping bag to the wall and…sweet dreams! 

Link: http://science.howstuffworks.com/sleep-in-space1.htm 

Link: http://astronautabby.com/the-international-space-station-time/ 

7.- Is there any other planet where we can live? by Lydia 

There is none so far. There are 31 exoplanets that we know that they have liquid water on its surface, or they are just on the right position orbiting its star,  but they are so far away that we should spend years and years in space just to reach them. 

But having a potentially habitable exoplanet doesn’t mean that it is actually habitable. It means that it has the conditions to develop life on it…but we don’t know if we could go there and live. Mars is on the (edge) of the habitability, but there’s no life there today (with today’s knowledge). 

Link: http://phl.upr.edu/projects/habitable-exoplanets-catalog 

8.- What would happen if all the planets were in the same orbit as Mercury? by Maria del Mar 

They will crash into one other’s. Eventually they will form a very big and massive planet, orbiting very quickly. The orbit (the year) of Mercury only lasts 88 days…so that will be in the beginning. But regarding the mass of the new super planet, it will have a big momentum (a lot of centrifugal force) so its orbit will make itself bigger and bigger, until the orbit and the centrifugal will match and stabilize the orbit. 

So…it will be a big mess around the Solar System, that’s for sure. 

9.- Is it possible that the Sun disappears and a new one appears? by Maria Magdalena 

It’s not only possible but certain that this is what it will happen in the future. In about five thousand million years, the sun will reach the end of its life. Then it will grow and grow and grow, gobbling down Mercury, Venus and the Earth. Then it will make an explosion and start to lose all its layers, that there are going to harvest with nitrogen, oxygen, helium and other materials the neighborhood of our System. In the very place where the sun was, it will remain its core: a kind of star called a white dwarf. 

This new star will be small, very small: the size of the earth. But with the mass of the original sun.  So from that moment, the Solar System it will be a dark place, without the power of the sun. The new white dwarf will cool down slowly, until it will became a new kind of star: a black dwarf. 

Link: http://www.universetoday.com/108734/what-is-the-future-of-our-sun/ 

10.- How big is the Sun? by Marina 

The sun is the biggest object in the Solar System. It’s about one million times bigger than the earth, so that’s a lot. 

Link: http://www.suntrek.org/sun-as-a-star/sun-and-earth/comparing-size-sun-and-earth.shtml 

11.-  Can you hear properly in the space or the voice changes? by Fátima 

Good question! The sound needs a medium to travel, so in space you can hear no sounds at all. 

But if you are in a spaceship, like the International Space Station, they have air up there, so you can hear yourself exactly on the same way than in the earth. 

Link: http://www.qrg.northwestern.edu/projects/vss/docs/space-environment/1-is-there-sound-in-space.html 

12.- When do you think we can travel to another Solar System? by Mateu 

Unfortunately, not in the next one hundred years (possibly). If you ask me, today is impossible. But we don’t know what is going to happen tomorrow. If something we know for sure in science is that what looks impossible today will look very difficult tomorrow and hard in the future. Hard but possible.  

So, to travel to the next Solar System (Proxima Centauri System) at the speed of light, will take us about four years. With the fastest ship we ever built…hundreds of thousands of years. The space is VERY big. 

But who knows…maybe among you there’s the next physicist who will develop a faster-than-light engine and we will be able to place ourselves in Proxima Centauri in a matter of hours. 

Is up to the science!  

13.- How astronauts throw the rubbish? by Viktor 

They don’t! They keep all the rubbish in a tank and this tank is taken by automatic probes to get burned in the earth’s atmosphere or take down to the earth to reprocess. 

Link: http://www.telegraph.co.uk/news/science/space/10287766/Space-station-crew-launch-cargo-ship-full-of-rubbish.html 

Link: http://www.csmonitor.com/Science/2014/0218/What-does-Space-Station-do-with-its-trash 

14.- What would happen if the suit breaks while you are floating? by Eva 

It have happened a couple of times, and it’s a danger. It the suit breaks a little, you just hold the hole until you are back to the ship (this is usually what happens). If you are not aware of the break, the danger is losing all your oxygen much faster than it is supposed to. But from the inside of the ISS and from the land (from Baikonur and Houston) there are a lot of people who is paying a lot of attention to avoid this kind of problems. And if a micrometeorite strikes on you and you have a hole in your suit…you will notice for sure. 

15.- How do you go to the toilet? by Adrià R 

You basically go the same way than in a plane, but with some differences.  The space toilet has a vacuum engine that sucks down all the “big” things than you deposit there. If you want to urinate, there’s another part of the toilet you urinate in, that holds the pee in a different deposit, to get recycled.  

Link: https://en.wikipedia.org/wiki/Space_toilet 

Link: https://www.youtube.com/watch?v=fa3nuXxM8yk 

16.- How are the stars created? by Dani 

The stars are created in huge clouds of dust and gas called Nebulae. The gas gets together and accumulate due to the force of gravity, until they rich enough mass (they got fat) to start causing nuclear reactions in the atoms that form the cloud (basically hydrogen). When that occurs, an explosion happen…giving birth to a new star. In the birth of a new star two forces play a very big role: gravity to get all the possible mass together and nuclear force to create light, heat and new elements of the periodic table. In other words, to create a star. 

Link: https://www.esa.int/esaKIDSen/SEMY06WJD1E_OurUniverse_0.html 

Link: http://www.cosmos4kids.com/files/stars_develop.html 

17.- What would happen if there wasn't any moon? by Danylo 

Gooooood question! It won’t be any more romantic walks in the light moon with my girlfriend, among other things. 

It turns out that the creation of the moon caused a big impact on the earth, because a small planet called Theia impacted with our planet, and the remaining debris got together to create the moon. So, with its birth the moon almost destroyed the earth. 

But it didn’t. What it did was to stabilize our planet’s axis. So with this stability our planet had become a suitable place for life to be developed. 

The moon gravitational pull had slowed down the length of the days: a couple of million years after the moon was created the day length was approximately ten hours. And now is more than the double: 24! 

So, if the moon wasn’t there probably neither we will. 

Link: https://en.wikipedia.org/wiki/Theia_%28planet%29 

Link: http://www.damninteresting.com/life-without-the-moon/ 

18.- How long can you be in the space? by Noemi 

Normally the astronauts in the ISS remain there a couple of months. The astronauts who went to the moon stayed up to ten days in space, but the top of time a person can stay in microgravity is recommended as a year (12 months). You can suffer physical problems and health problems if you stay longer than that. 

However, the record of time in space belongs to a Russian, called Valeri Poliakov; who stayed in orbit 14 months in one trip. 

Link: https://en.wikipedia.org/wiki/Valeri_Polyakov 

19.- What would happen if the gravity disappears? by Núria 

It will be a very bad day for everyone. The only way that gravity disappear will be it the Earth were empty. Let’s assume that for a moment. 

If the Earth suddenly had no mass, just the empty crust, we wouldn’t have almost any gravity at all. So the first consequence will be that everything will start to float around. You, the desk, the pencil, the teacher…nothing would remain in its place. 

That will bring a complete chaos in the planet, because nothing will remain on its place. Imagine you go to bed and the bed is floating…with the lamp, the closet, your clothes, the carpet, everything.  

The good thing is that you will just need a fire extinguisher to travel around! Imagine that: you grab a fire extinguisher and you push the trigger of it. You will be casted away in the contraire direction…with no stop until you push the trigger back in the other direction. And that means going anywhere around the planet…or straight to space. It will be a very cheap way to go to Mars though. 

22.- How can astronauts land back in the Earth? by Nico 

The astronauts come back to the earth in Russian probes called Soyuz. They sit down in a capsule and it goes falling down. It has a couple of thrusters to control the descend, and a very strong parachute as well. When the probe is close to the ground (always in Russia) the thrusters got on and that slow down the landing, becoming a “soft landing”.  

So basically the astronauts are throw down to the Earth. 

Link: http://www.slate.com/blogs/bad_astronomy/2014/06/08/back_to_earth_how_astronauts_get_back_from_the_space_station.html 

23.- What we see in films is what would happen in real life? by Diana 

Assuming that you are referring to astronautics and astronomy the answer is, unfortunately, NO. In almost every single movie that plays some concepts of astronomy or astrophysics is wrong and it’s not how it works. 

For example, the spaceship in the Star Wars saga doesn’t move AT ALL the way they are supposed to. They look like planes, but if there are in space…they don’t have an atmosphere to interact with. 

Some movies are very accurate, as Interstellar or 2001: A Space Odyssey. Or even the Star Trek franchise. 

But generally the science seen in movies has nothing to do with real science, sadly. Don’t trust them to explain science. 

Link: http://www.badastronomy.com/bad/movies/ 

24.- Has the Sun always been orange as we see it now? Has it ever been kind of blue? by Diana 

The sun is white. But we see it orange only when is rising or setting, close to the horizon. That’s because the sun light have to cross more atmosphere when is low and the color that we see it isorange, because of something called the light’s diffraction. But when is high in the zenith, at noon, above our heads…the sun looks yellow. But that’s another history!  

If you ask any astronaut how the sun looks like in space all of them will answer that it looks at it is: white. 

And the second question: It has never been blue. It’s too small for that. The biggest stars begin their life being blue, and then go to white, orange and finally red. The sun isn’t big enough to that, so it was born white and it remains white still now. In a couple million years will turn orange and finally red.  

The sun, scientifically speaking, is a “G” Star. You can have more information about that in the links below. 

Link: http://www.universetoday.com/18847/life-of-the-sun/ 

Link: http://io9.com/5963520/when-the-sun-turns-blue 

Link: https://en.wikipedia.org/wiki/Stellar_classification 

25.- What happens when a star dies? by Diana  

It depends of the mass of the star. I already explained what will happen to the sun, but not to a bigger star. Let’s do it. 

If the star is between the size of the sun and 8 times that mass, it will finish with a low energetic explosion and with a white dwarf star on its core, a star the size of the Earth but the mass of the sun. 

If the star is between 8 and 20 times bigger than the sun it will finish its life with an enormous explosion called supernova that will let in this center what is called a neutron star or pulsar. That’s a star the size of Palma but with the mass of the sun (amazingly dense). 

But…if the star have more than 20 times the mass of the sun, it dies with an enormous explosion (supernova) and in its place a black hole is born. That is a star with no volume at all but with an infinite mass, what we call a paradox.  

So, a star always dies (and is born) with an explosion. Depending on the mass it can be less or more powerful.  And the remaining of this explosion, the element that remains in the place of the star, it can be a simple dead star or something that we discovered just in the last century, a black hole that swallows everything including light itself.   

Link: http://www.livescience.com/32879-what-happens-to-earth-when-sun-dies.html 

Link: http://www.kidsastronomy.com/black_hole.htm 

Link: https://www.esa.int/esaKIDSen/SEM0V1BE8JG_OurUniverse_0.html 

Link: http://coolcosmos.ipac.caltech.edu/cosmic_kids/AskKids/blackholes.shtml