By Bethan Evans, Gwen Jackson, Siobhan Waters and Amy Folkard – the astronomers of Year 9, LGGS

1. EXOPLANETS, SUITABILITY FOR SUSTAINING LIFE AND GILESE 1214B By Bethan Evans, Gwen Jackson, Siobhan Waters and Amy Folkard – the astronomers of Year 9, LGGS

2. Please watch Video 1: An Introduction:

3. What is an Exoplanet?

4. Please watch Video 2: What is an Exoplanet?:

5. What is a planet? The word planet comes from the Greeks describing celestial bodies as ‘asasteres planetai’ which translated means ‘Wandering Star’. A planet’s definition is then seen as a celestial body orbiting round a star. Planets are made up of supernovas exploding and sending many materials into space, such as carbon, oxygen and iron.

6. What is an Exoplanet? An Exoplanet’s definition is a planet orbiting a star located outside our solar system. An Exoplanet or extra solar planet can range from large gaseous planets such as Jupiter from our own solar system to dwarf planets such as Pluto. Exoplanets often orbit stars similar to our own sun, which makes it even more possible that there are planets similar to Earth in the galaxy, as many astronomers believe there are 17 billion earth sized planets located in our galaxy.

7. Discoveries of Exoplanets Since the start of detecting Exoplanets in 1992 over 1,000 Exoplanets have been discovered so far. A study took in 2012 shows that scientists believe that out of the three billion stars in our galaxy one billion of these will have 3 Exoplanets or more. this means that there are approximately 2 billion Exoplanets still to be discovered!

8. Which Exoplanet Did We Choose?

9. Gilese 1214b The reason we chose Gilese 1214b is because it is perfect for human existence. It has a suitable: • Gravity score • Atmosphere • Density / terrain • Goldilocks zone We also had to consider other things before making our decision, such as: • How to detect an Exoplanet • The effect on the body • Other aspects we need to know about Gliese 1214b • What if the planet is already inhabited?

10. How Do You Detect an Exoplanet?

11. Please watch Video 3: How to Detect an Exoplanet Part I:

12. Please watch Video 4: How to Detect an Exoplanet Part II & How to Detect an Exoplanet Part III:

14. Now that we know what an exoplanet is, the next problem is to find one. This is a very difficult process, seeing as planets do not emit any light of their own. So we cannot look for one simply by looking through a telescope, partly because they are so far away and partly because of the fact that, unlike stars, they do not emit light, they only reflect it so are just about invisible because it is impossible for even out most powerful telescopes to differentiate between the light of a star and the light reflected by a planet.

15. We have many different methods of detecting exoplanets. For example, the Optical Gravitational Lensing Experiment group (OGLE) are experimenting with one type of detecting planets which takes the theory behind its method from Einstein’s General Theory of Relativity. Einstein said that massive objects in space can bend light on its way to Earth. This is just one way of detecting massive exoplanets.

16. The Transit Method uses the moments during which a planet passes directly between its star and our Earth. It is the most successful way of finding a planet yet found, and has helped to discover most of the planets which we have found so far. For example, Gilese 1214B was found using this method, so we know that it has been practical in finding the exo-planet which is most important to us in this investigation.

17. An example of transits closer to home is the transit of Venus which happened in the summer of 2012. This was one of the few transits of Venus which we will be able to see – they happen in pairs, and the next won’t happen until 2117! An extreme example of a transit is a solar eclipse. This happens when the moon passes directly between the Earth and the Sun and completely blocks the Sun’s light.

18. Obviously the transits which we are trying to detect are nowhere near as obvious as the closer-to-home transits. In fact, trying to look for a planet using the transit method is like trying to detect a fly flying in front of a lamppost by looking at the light it blocks out – when standing a kilometre away! The only way we can tell that they are there is by looking for regular dips in the light emitted by the star that they orbit. We can use the size of these dips and the amount of time between them to help estimate the size and orbit length of the planet we have detected. If they appear enough times, at constant intervals and sizes, then we can assume that we have found a new planet.

19. We set up an experiment to investigate the transit method for ourselves. This experiment used polystyrene balls as planets and a light bulb for a star, and showed us the ideas behind the transit method. We ended up with four different graphs telling us about the transit method, which will be explained in the next few slides.

20. Graph 1 – Smaller Planet, Middle Distance from the Planet, 5 second Intervals. The dips in the amount are quite big, because as it is further away, the planet blocks out more light. Also, their frequency is smaller than when the planet was closer to the star.

21. Graph 2 – Smaller Planet, Close to the Light Source, 2 second Intervals This time the dips are smaller because the planet is close to the light source, and more regular because the intervals were smaller.

22. Graph 3 – Bigger Planet, Middle Distance from Light Source, 5 second Intervals On this graph, the dips are very big compared to the other graphs. This is because the planet is big and far away.

23. Graph 4 – Bigger Planet, Close to Light Source, 1 second Intervals Altogether from this experiment we can find out that the bigger the planet, the bigger the dips in the amount of light. Also if it is far away from its star then it will often block out more light than if it is closer.

24. The Goldilocks Zone

25. Please watch Video 5: The Goldilocks Zone:

26. One of the most essential criteria which an Exoplanet must fulfil to be counted as possibly habitable is to be within the boundaries of the Goldilocks or Habitable Zone. This is the specific area away from the star it orbits where a planet is able to sustain liquid water: too close to its star and all water on the planet would evaporate; too far away and it would freeze. The temperatures too close and too far away would be impossible for sustaining human life. This is why any planet we consider for our new home must be within its star’s habitable zone.

27. Of course, whether a planet is in the Goldilocks Zone, so called because the conditions must be ‘just right’ like the third bowl in the children’s story ‘Goldilocks and the Three Bears’, is not the only variable to consider when deciding whether Gilese 1214B is suitable for human life. Atmosphere also plays a big part (which we will talk about in more detail later): for example, even though Earth is definitely in the Habitable Zone, processes such as Global Warming mean that in the future it may become unsuitable for human life.

28. The first step in finding out whether an Exoplanet is in the Habitable Zone is to work out how light spreads and therefore decreases its input to any one area of a planet as the planet gets further away from the star. We set up a basic experiment to explain the theory behind this. This experiment showed us that the further away the ‘planet’ is from the light source, the more spread out the light is and therefore the less light and energy each square metre receives. This can be calculated using something called the ‘Inverse Square Law’. So if the light source is twice as far away, then the light will be 22 or 4 times as spread out, and so on.

30. Calculating the Habitable Zone of Gilese 1214 Inner Boundary Outer Boundary We then compared this to the semi-major axis of the planet in question. The semi-major axis of a planet is a way of measuring how far a planet is from its star so that this measurement is fair. The semi-major axis of Gilese 1214b is 0.0143, which is between the two values worked out above – which means that Gilese 1214b is within the Habitable Zone!

31. *The semi-major axis of an exoplanet is measured in AU or Astronomical Units. This is a measurement used to prevent having to work with huge numbers of kilometers/miles. One AU is the same as the distance from the Earth to the Sun.

32. What would Gilese 1214b’s Atmosphere be like?

33. Please watch Video 6: Atmosphere:

34. We can work out a planet’s atmosphere using what is called a spectroscope. These instruments are used by astronomers to help figure out which chemicals can be found within a planet’s atmosphere, using the light which passes through it. For example, the Earth’s atmosphere contains a lot of nitrogen, and enough oxygen for we humans to survive, as well as other elements. Without this atmosphere the Earth would be unable to sustain life.

35. The spectroscope relies on the fact that white light can be split up into a whole spectrum of rainbow colours. For example, a rainbow as we see it in the sky is made when raindrops split up the sun’s ‘white light’ into the visible spectrum. Certain elements which can be found in a planet’s atmosphere absorb certain colours of light. For example, you would be able to tell if sulphur is in a planet’s atmosphere because it absorbs a certain type of yellow light. Each element has its own specific type of light, which is very useful for detecting them in a planet’s atmosphere.

36. So when we look at the spectrum of light which is passing through an exoplanet’s atmosphere, we can see tiny scratches where there are types of light being blocked. These can also be transferred to graphs, which show dips in the light which is passing through a planet’s atmosphere. This is called ATMOSPHERIC DISTORTION

37. We have used this method to work out that the atmosphere of Gilese 1214b would be suitable for life, which means that we are one step closer to having a planet which we could live on. Without a suitable atmosphere, a planet would be completely unsuitable for life. Our Earth’s atmosphere currently protects us from harmful sunrays, makes sure that water on Earth is kept on Earth and generally makes the planet suitable for life. Venus, however, has an extremely dense atmosphere which would crush anyone who tried to go there, and Mars has little to no atmosphere, meaning that all water on Mars would not be sustained. So both of these planets, which are quite like Earth, would be unsuitable for life, and atmosphere plays a big part in this.

38. What is the effect of the Gravity of a Planet?

39. Please watch Video 7: Gravity:

40. Gravity is vital to survival on an exoplanet. If there is too much gravity we will be flattened against the surface but if there is too little we will float. We can work out the Gravity Score with the formula: Gravity Score = mass/radius squared. The Gravity Score of Gliese 1214B is 0.9133140836.

41. What is the effect of the Density of a Planet?

42. Please watch Video 8: Density:

43. Density is very important when you are trying to find out if a planet can support life. If it is not dense enough your will fall through it but if it is too dense you won’t be able to walk on it. To find out how dense Gliese 1214B was, we used the method Mass/Volume = Density. The density of our own planet, Earth, is 5.5 g/cm3. Gliese 1214B’s density is 1870 kg/cm-3.

44. What else Should we Know About Gilese 1214b?

45. Please watch Videos 9 and 10 – What else do we need to know Parts I and II:

46. What if Gilese 1214b was already Inhabited?

47. Please watch Video 11: What if we Found Aliens?

48. If we get to Gliese 1214b and find out that it is already inhabited by aliens, what would be the protocol? Well you would have to approach them with respect and gifts, to try and make peace with them so we can live together. As Gliese 1214b is so much like earth and human can survive on it, hopefully the aliens should be just like us. This means they may have enough intelligence so that we can communicate with each other successfully. We could share our knowledge with each other, to widen our knowledge of the universe. Even though we are evacuating everyone (hopefully) we still might not be able to bring all of our traditions and agriculture with us.

49. … so as a solution we will bring with us many things to remind us of our old ways and so we can teach the aliens as well.

50. Thank you for watching/reading! With the help of all our top scientists, we will definitely be able to move the whole of the human race to Gilese 1214b.