Sunday, 6 December 2015

Exoplants - The Worlds Beyond


While I had heard about the discovery of the first planets beyond our solar system I hadn't really been keeping up with the news of such discoveries, despite the fact that I do really like my science fiction. Sure, there are planets orbiting stars that aren't our sun, but considering the distance that one has to travel to actually get to the closest one I didn't see much point in paying huge amounts of attention (but then again that was back before the internet where most of our news came either through the television or the newspaper and if we wanted to find out more we have to go to dedicated scientific journals).

However, as I was perusing through some of the rather interesting short videos on the internet I came across this one:



The first time I watched it I said to myself 'gee, that's interesting' and then continued on with my daily life. I knew that they had worked out if a star had a planet around it, but hadn't thought all that much about it beyond that. I then watched another couple of videos about planets on Youtube, and the two planets that kept on coming up were the planet made entirely of diamond and the planet where glass rains sideways.

Hold it, I said to myself, how do that know that this planet is made entirely of diamond, and that there are constant glass storms on this other planet - aren't they like light years away? Surely we don't have a telescope that is that powerful? Well, the answer to that question is that a lot of it is speculation, or probably the better description would be an educated guess. However, it still left me wondering how they could find out so much about these planets when not only are they so far away, but we can't actually see them with a naked eye.

The Discovery

PulsarWell, as with everything that I am curious about my first port of call is none other than Wikipedia. My first impression when I began to read through the article on exo-planets (the term used for planets that don't orbit the sun) was that it must have been written by a scientist. Actually, I wouldn't be surprised if this article was regularly updated by scientists working in the field (which I have to say it would be pretty cool to get paid to write wikipedia articles). According to this article, the first planets were discovered in 1992 orbiting a pulsar (which is a highly magnetised rotating neutron star and it receives its name by the electro-magnetic pulses that it sends out), however the first planets orbiting what they call a main-sequence star (namely a star that hasn't exploded or collapsed) was in 1995. Mind you, with the technology that they had at the time the only planets we could detect where those around the size of Jupiter (and since these planets were really close to the sun they took the name hot jupiter), however that has since changed with the launch of the Kepler telescope in 2009. To date 1953 exo-planets have been discovered in 1250 planetary systems (though that could have increased since I original wrote this).

So, the question is - how do they find them? Well, as with a lot of things they resort to the use of light. The thing is that light is absolutely amazing - it is more than just that warm glow that emanates from an electric filament that prevents us stubbing our toes or banging our knees as we walk across a room (though we still need to look where we are going). In fact light, or more precisely the electro-magnetic spectrum (which is a scientific word for light, though it goes beyond what is known as the visible spectrum) is the basis of modern communication. You know that little wi-fi symbol you see at the top corner of your phone and computer? Well, it is light that allows you to magically connect your computer with the modem on the other side of the room without the need of a cable. In fact it is light that allows you to dial a number on your mobile phone and speak to somebody on the other side of the world. So, as you are probably aware, light does a lot more than simply allowing us to see.

The electro-magnetic spectrum
Now, there are two types of objects in the universe (and this is probably one of the very few places that you can actually categorise things, though somebody is probably going to pop up and prove me wrong): Luminous and Reflective. Luminous objects produce light, such as a star, and reflective objects reflect light (obviously), such as a planet. As such, when something passes between you and your kitchen light (such as a moth) then the moth will cast a shadow across the room since the moth is reflective. The problem is that a star is this massive light sitting on top of a building a kilometre away from you, and the planet is like a moth passing in front of that light - basically you won't be able to see it with the naked eye. This is known as a transitioning (namely when the planet passes between us and the star). However, being the clever people that they are, the scientists managed to tweak their telescopes, and after a long time searching, finally discovered their first planets.


Okay, so they found a star with some planets around them - what next? Well, they had to work out what these planets were like. Once again, being the clever people that they were, they figured out a few things. First of all reflective objects are quite funny - they don't just reflect light, they also absorb light. So, you know that blue book that I assume is sitting on your desk, well it absorbs all of the light with the exception of the blue, which it reflects - that is why you see it as blue. Now, because of these funny things that light does, scientists are able to actually read the light signals that are coming from these places and as such are able to speculate (or make educated guesses) on the make up of these planets.

Oh, and there is another strange phenomena that I recently discovered. Planets don't just orbit a star, their gravitational pull will actually make the star move around a point in space. You know how you were taught in school that the sun was the centre of the solar system? Well it turns out that, once again, your teacher was wrong. No, the centre of the solar system is actually a point in space that the sun moves around, as can be seen in this gif below.


Transiting Planet

I won't go into too much more detail about how they detect the exo-planets and how they work it out, but if you are interested you can always go to the Wikipedia article (though it is incredibly technical).

The Kepler Experiment

Well, scientists being scientists weren't simply happy to look at the stars from the comfort of the Earth, they wanted something more powerful so they could attempt to find more stars with more planets, so they managed to convince the government to give them a heap of money so they could send a telescope up into space with the explicit purpose of finding planets (and why the government was happy to give them money, though happy is probably not the best word since I suspect the scientists had to do a lot of grovelling to get that money, I'll explain a little later). Anyway, they named this space telescope Kepler, after the guy that worked that those strange stars bouncing all over the night sky were actually planets orbiting our sun, and sent it up into space to continue their research.


Anyway, the idea was that Kepler would sit in orbit around the Earth looking at a specific point in the sky and collect data from the stars that sat in its field of view. Okay, while it may only be looking at one small spot in the sky we have to remember that in that one small spot there are an awful lot of stars, and sure enough as soon as the telescope opened it started receiving all of this information. In fact as of January 2015 Keplar has discovered over 1000 exo-planets with 3600 unconfirmed planetary candidates (meaning that there might be a planet around that star) and 2100 eclipsing binary stars (stars which orbit each other).


Unfortunately for the scientists in 2012 one of the reaction wheels (which are used to keep Kepler pointing at the same area of space) broke down, and while it could still operate and be useful, in 2013 a second wheel broke making it all but useless. However, all was not lost for in the three odd years that it was up there it had managed to collect an enormous amount of data which I suspect that scientists are still trawling through.

Kepler Solar Array
The problem was that simply seeing something pass in front of a star does not necessarily mean that there was a planet there, which is why Kepler needed to continue to point at that section of space. To be able to determine whether there was a planet orbiting the star (or as it has turned out, stars - yes, there are planets like Tatooine orbiting two stars out there) the transition had to occur at regular intervals.  This worked well for planets with small orbits, but the longer the orbit, the more time you needed to be able to watch the star. For instance Jupiter takes twelve years to complete one orbit of the sun and Saturn takes twenty nine years. Just because something transitions past a star does not necessarily mean that we are seeing a planet orbiting it.

If you are really interested in the technical aspects of the telescope check out the Wikipedia article.

So Who's Paying?

The government of course. NASA, being a government agency, pretty much receives all of its funding from the government (though I'm sure the private sector helps as well, especially if they are using it's services, but then again when it comes to government departments everything they earn tends to go back into the government coffers). NASA was initially created because the Soviets were beating the United States in every aspect of the space race, though putting that first satellite in orbit sort of gave the government a major impetus to get on board. However now that the Russian's are gone, the need to get the better of them has sort of disappeared.

However, that one satellite that the Russians flung around the planet has pretty much changed the world that we live in. The fact that we have literally mapped every corner of the Earth (even though we haven't visited every corner of the Earth) is thanks to the space race. These satellites have made this modern world of mobile phone technology (and electronic surveillance) a possibility. However, like most things, if it wasn't for the Russians, nobody in the US government would have seen any economic benefit in attempting to conquer space, and would have left it as is.


However, what economic benefit is there in looking at a bunch of planets orbiting other stars? To find another Earth of course (though the fact that at our current technology by the time any spaceship actually arrived the entire crew would have died of old ages doesn't seem to stop them). Sure, searching for resources might be a possibility, except that with the planets in our solar system the need for resources is a moot point (and while I believe seeking resources off world would be a much better option than digging up our own planet, there doesn't seem to be a huge amount of will to take that step), but finding another Earth-like planet is basically the goal of this mission (though since much of the data that we receive from the planets allows us to basically make educated guesses doesn't seem to stop the hunt).

Some Interesting Discoveries

Well, what I might finish off doing is looking at some of the planets that Keplar has discovered and saying a few things about them. Pretty much all of this information comes from Wikipedia, but as I've said before I write for pleasure and try not to write as if I'm some sort of encyclopedia. Once again, you can find the full list of exo-planets on wikipedia (I suspect the NASA scientists probably update it). Oh, I'll also be giving these planets my own names because, well, the names that the scientists give them are rather boring, but I will list them by their official name (as well as linking it to the page).

Keplar 9b - PrimusKepler 9b: I'll call this planet Primus, not because it was the first planet discovered by the Kepler Mission, but because it is one of the first (and looking at the list on Wikipedia it is the first one you can click on to open a page). Basically it is a gas giant, but it is slightly smaller than Saturn, and shares the system with another planet (named, ironically, Kepler 9c). The other interesting thing about this planet is that it demonstrates a property known as orbital resonance, which basically means that the gravity of it and it's sister planet act upon each other to maintain their orbit around the star.

Gliese 1214b: I don't have to give this planet a nick-name because the scientists have already done this for me - Waterworld (though don't expect to find Kevin Costner running around on it's surface). They call this planet a super-Earth because it is bigger than Earth, but nowhere near as big as the gas giants. Okay, this thing about being a water world should be tempered with the words 'most likely candidate for' because the scientists haven't actually determined it's exact composition. However what they can say is that it is probably cooler than many of the other planets, and that it is suffering what they believe is atmosphere loss (meaning that the atmosphere of the planet is leaking off into space). By the way it happens to be only 45 light years from Earth, but considering it would probably take us centuries to actually get there, that minor thing probably doesn't help all that much.

HD 154672 b: Okay, maybe I'm not the best person to go around naming planets, but for the sake of it lets call this place 'Magnesia'. Why? I really don't know - it was the first name that popped into my head (though I'm sure people are going to start getting really stretched if they start giving all these planets proper names - which is probably why they resort to numbers - they are even resorting to naming stars after ordinary people, for a price of course). Anyway, this is what you call a Hot Jupiter (more on that later) as it is a gas giant that happens to be bigger than Jupiter. Other than the fact that this planet has a decent sized entry on wikipedia, it also has a rather strange orbit. While the orbit is elliptical, it also happens to bounce about rather erratically. Oh, the star apparently has a lot of metals in it (determined by using various scientific instruments) so this planet is of interest to see if the high metallic concentration in the star has an effect on the planet.

OGLE-TR-10b: - This rather large planet is another example of a Hot Jupiter, and can be found orbiting a star in the constellation of Sagettarius. While I could give it a name sticking with the nomenclature standard of using Greco-Roman gods, I think I will grab a name from Dungeons and Dragons and call it Mephitophenes (who happens to be a demon in the Judeo-Christian mythology). Even though I have provided a link to the Wikipedia entry on hot Jupiter, I'll say a few things about these planets here. The reason they are called hot Jupiters is pretty straight forward - they are gas giants (not necessarily larger than Jupiter) that orbit pretty close to their star, meaning that they are really hot. This planet is probably really close because apparently it's orbit takes something like four days. Oh, and if you are wondering about the name, they come from the telescope that discovered the planet (in this case the Optical Gravitational Lensing Experiment, or OGLE for short - I wonder if they came up with the abbreviation before they came up with the name?).

Gliese_876_b: This planet was detected differently to the others - rather than picking it up when it passes in front of the star, it was detected through it's gravitational pull, which means that we know a lot less about it than some of the other exo-planets. Okay, you may then ask why I have a picture of it - well, that's because somebody created one, though I'm sure painting a picture of an unknown planet is not too hard - you just create a circle on some random drawing program as fill it in (though these artists do a much better job than I would). Anyway, this planet is of interest because it sits just outside the habitable zone of the star, the zone where scientist theorise that they might find a planet that is habitable like Earth. In fact they refer to it as the Goldilock's zone - it isn't too hot and it isn't too cold. However, Gliese 876 B (which I'll call Eurora for some unknown reason) is a gas giant, so scientists are speculating that its moons might actually be habitable. Okay, it sits just outside of the zone, but they believe that the zone is slowly moving outwards so, in maybe a million or so years, it might become habitable. Still, it's a little bit too long to wait around - they probably should look elsewhere.


HD 189733b: Lets call this planet Tempus (after another god from Dungeons and Dragons, though Ed Greenwood stole that name from Norse Mythology). Why? well this planet is famous for the fact that it rains glass sideways. Okay, that's probably misstating the property of the planet a little because more likely than not it is one whopping great big storm in which tiny shards of crystal fly around at incredible speeds, similar to how incredibly strong gusts of wind can pick up objects and send them tumbling down the street (or to put it more precisely, the way storms in deserts pick up the sand and send it spinning around - I've been caught in a dust storm and I have to say that it is not a pleasant experience). Surprisingly they know quite a lot about this planet, right down to its colour. In fact it is the first exo-planet that they have managed to work out its colour. They have even apparently mapped out it's surface to some extent. Anyway, the reason they say that it is one huge storm is because they believe that the planet is tidally locked, meaning that one side is always facing the star. This causes that side to heat up incredibly, but the far side becomes incredibly cold. Anyway, as the hot air rises this causes the colder air to move in to fill the vacuum causing the pressure on the far side to drop, which the hot air then moves in to fill up. Oh, I also noticed that the discovery of this planet has also appeared on some news sites.


55 Cancri e: I'm going to call this planet 'De Beers' namely because it is allegedly made of one huge diamond and if Michael Alcubierre manages to get us there with his warp drive then it is going to completely bankrupt them (the only reason diamonds are so valuable is because of the perception that there are so few of them, or at least so few of them available for sale - a planet made entirely of diamond is pretty much going to cause the price to fall out of the bottom of the market). Okay, they don't actually know whether it is made of diamond or not, it is just that they suspect that is it is possibly made of carbon which means that the pressure in the centre of the planet is going to cause the graphite to turn into diamond. It is actually the first super earth to be discovered around a main sequence star (basically a super-Earth is not a gas giant, and is bigger than Earth). Fortunately for De Beers, the planet is 40 light years away so we won't be getting there any time soon.


HD 209458 b: This planet actually has a name, even though that name is unofficial, but they call it Osiris. The reason this planet has been given a name is because it represents a number of firsts. It was the first planet detected by the transiting method, the first planet detected through more than one method, the first planet known to have an atmosphere and an atmosphere with not only both oxygen and evaporating hydrogen, but also the first planet where water vapour was detected. It was also the first planet to be detected spectroscopically, to have it superstorm measured, and also the first planet to have its orbital speed detected. Well, I'm sure there are a few other firsts for this planet, but I'll leave it at that. I just wanted to mention it because it has a name.

PSR_B1620-26_b: This is another planet that's been given an unofficial name, and it is the only planet (so far) that has received a Biblical name, which is Methuselah. The reason that this planet is called Methuselah is because it is really, really old (just as Methuselah was reported to be the longest living human recorded, at least in the Bible). Anyway, this planet orbits a pair of stars, one of them a white dwarf, the other a neutron star that spins really, really fast (otherwise known as a pulsar). This planet wasn't discovered through the transiting method, but rather due to doppler shifts against the white dwarf. Since planets generally don't survive supernovas (which give rise to neutron stars) Methuselah is believed to have originally orbited the white dwarf but was pulled into the orbit of neutron star afterwards.

Anyway, while I could probably write a lot more on exo-planets, I will probably call it a day here (since I have written quite a lot already, and have a lot of other things to do as well - anyway, I guess my fascination with exo-planets has begun to wane since I started writing this post). If you are really interested in this topic, then there is lots of information on the internet, however I guess my interests have been hijacked by other things now.


Creative Commons License
Exoplants - The Worlds Beyond by David Alfred Sarkies is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.If you wish to use this work commercially please feel free to contact me.

"EM spectrum". Licensed under CC BY-SA 3.0 via Wikimedia Commons
 "Exoplanet Comparison GJ 1214 b" by Aldaron, a.k.a. Aldaron - Own work, incorporating public domain images for reference planets (see below), inspired by Thingg's size comparison. Licensed under CC BY-SA 3.0 via Commons
"OGLE-TR-10 b and Lagoon Nebula" by Tyrogthekreeper (talk) - I (Tyrogthekreeper (talk)) created this work entirely by myself.. Licensed under CC BY 3.0 via Commons
"Gliese-876 b" by JohnVanVliet - Own work. Licensed under CC BY-SA 3.0 via Commons 
"Artist’s impression of the deep blue planet HD 189733b" by ESA/Hubble. Licensed under CC BY 3.0 via Commons
"55 cancri e (Celestia)" by Kirk39 - Celestia. Licensed under GPL via Wikimedia Commons

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