User blog:Cerne/Additional research

Yes, it has been a long time, and no, I haben't gotten any work done on my article's data table. I am going to try and get some work done on that as soon as I can. There is nothing getting in my way, as there was before (I think), but I have been busy with a few other things lately. Mostly offline stuff, actually, but I have been doing a few things online, too. Extra research never hurts anyone...

While I have been attempting to get myself back on track with my article, I have been thinking about a few more things concerning my planet. In particular, what it will look like and what kinds of geological activity it will have. I have some sources for the latter - both online and offline - and am going to look into it more when I get the chance to. I now have a good enough idea of what my planet is made of so this should make things a little bit easier.

As for the former... My planet orbits an orange dwarf star so the luminosity will be lower here than on Earth. UV levels will be lower, and this means photosynthetic plants living on the planet's surface will get less UV radiation for photosynthesis. They also get a shorter daytime period due to faster rotation and hence shorter days.

Luminosity actually determines brightness; for higher UV levels we want an older or more progressed (for lack of a better word) spectral type. A star's spectral type is a representation of its age; it indicates the star's mass, heat output, and relative size. Most main-sequence stars change spectral type as they age, but the younger stars that are higher in luminosity will get bigger and hotter faster because they will have burnt more of their hydrogen and helium. As a star increases in mass, it increases its luminosity and UV output. Stars that start out very massive crank out a lot of UV and are very bright and very hot, but they don't last long. So, for our purposes, we need a main-sequence star with lower mass which will give it less heat and UV but also a longer life.

To the right is a version of the Hertzsprung-Russel diagram for main-sequence stars. In it, you can see the surface temperature in degrees Kelvin at the bottom and the absolute magnitude of luminosity on the left. Stars that start out relatively cool but very bright are not as massive because they aren't burning avery much hydrogen and helium, but their radiation output is much higher because what they do have is much stronger and hence can provide more radiation per second.

Or something like that.

Anyway, back on my planet's surface, the plants will be getting less UV and they will need to indicate this somehow. Plants on Earth reflect green, which is the colour at the very center of the visible spectrum, because it is the highest wavelength of visible light radiation that they can reflect and just low enough that they won't absorb it. Anything lower than that is not used by the plant at all except as heat energy, and anything higher is used for photosynthesis, so green represents a boundary in the radiation wavelengths that reach the surface of Earth. The plants that are living on my planet will need to cope with lower UV levels so their boundary colour will need to be lower down in the visible spectrum, closer to the infra-red end. Wavelengths that are reflected will be longer and thinner, so the plants themselves will need to be more delicate to avoid breaking up the radiation as it hits the surface of their leaves (also known as the epidermis). Instead of being pure green, they may be a greenish yellow colour that is close to chartreuse (olive) or celadon, or they may exhibit the moss, tea, and harlequin variations of green that we have on Earth, because this is the highest visible wavelength of sunlight that they would be able to risk reflecting. Anything higher than that, like pure green, and the plants would not be able to photosynthesize properly.

The plants may not be the only things seen on or from the planet's surface that may look different. Even something as obvious as the sky and the clouds may be different from that of Earth. For a while now, I had assumed that if my planet's interior was denser, then so would my atmosphere. That, or it would be thicker. Or heavier. Or all three. In particular, I was attracted to some of the heavier noble gases like krypton and xenon. Namely these two; radon is radioactive so it is a no-go. Earth already has argon, and both helium and neon are too light to be of any interest. I wanted to do some research into where Earth's atmospheric argon came from because I thought it would be cool to replace the position that argon has in our atmosphere with one of the heavier noble gases. My best guess would be krypton because it is the next one down the line in group 18 (noble gases). It is also in period 4 along with iron. Why is this relevent? Because argon is right above it. The metals that make up my planet's core are in period 5, The easiest step in determining what noble gas your planet will have most of might as well be determined by finding the period that has your core's metal in it and finding the noble gas that is right above that period.

This site says - or more rather verifies (since I kinda already knew this) - that atmospheric argon is made up almost entirely of the stable isotope argon-40. The reason I suspected this is because there is a dating technique used for finding the age of older fossils called potassium-argon dating, which I learned about in a few of the university courses I took out west in B.C. years back. If potassium-40 decays into argon-40, and argon-40 is the primary argon isotope found in our atmosphere, then one of the elements that I will need if I want to have argon in my atmosphere is the alkali metal potassium. Looking through a very cool site called the Photographic Periodic Table of the Elements by Theodore Gray (I have his card deck), I find that other isotopes of argon also come from potassium. In addition, isotopes of calcium and chlorine decay into argon as well. Chlorine is on period 3 along with argon right beside it, but potassium and calcium are on period 4 on the other side of the table. Keeping this configuration in mind, I then move down to krypton. Low and behold, amongst the isotopes that decay into krypton are rubidium and strontium on period 5, and bromine on period 4. Selenium was in there, too. For xenon I get cesium and barium in period 6 and iodine in period 5. Same configuration. Going further, I find that stable parent isotopes for both gases seem to go lower in atomic number, or backwards up the periodic table, while radioactive isotope decay seems to go higher in atomic number, or forward down the periodic table. Ultimately, isotopes of krypton are derived predominantly from isotopes of technetium while isotopes of xenon are derived from isotopes of the lanthanide europium. As it turns out, all isotopes of technetium are radioactive and its density is very much like that of ruthenium and palladium, the two metals that make up my planet's core.

This is all good news for me because it means I can use krypton as a major component of my planet's atmosphere. Maybe even more than 1%. It goes well with the metals I am using for my planet's interior composition both in density and in where it is on the periodic table, and it is radioactive. Meaning, among other things, I may be able to use it for a story arc. In addition to krypton, my planet will probably need a lot of nitrogen in its atmosphere, followed by oxygen (obviously), then maybe carbon dioxide. Depending on the period in time that my planet is in, carbon dioxide levels might be lower or higher than those of krypton. And then there is water vapour, but this definately will vary depending on the environment in question. All other gases will probably be trace amounts, or their levels will be so low that they may not be worth mentioning. What I do want to consider is that - aside from possibly higher levels of sulphur due to (maybe) more volcanic activity - having krypton in my atmosphere means that I may also have bromiine. Bromine is a halogen, like chlorine and fluorine, so large enough amounts of it are toxic to carbon-based life forms. This includes the life forms on my planet. I will need to figure out how prevalent bromine will or can be in my planet's atmosphere.

Finally, Iwas curious as to whether what my planet's atmosphere is made of will affect what my planet's sky will look like or not. I did a search and came up with something called Rayleigh Scattering. This effect has more to do with colour than anything else, but it is still worth considering. On Earth, we see a blue sky because the radiation coming in from our sun is "scattered" by the molecules in our atmosphere and distributed across our sky. Most of the visible radiation coming in from the sun is high-level radiation and is visually represented by the colours blue and violet. That is why we see a blue sky. Lower levels of the visible spectrum are not strong enough to be scattered so they are not as evenly distributed. However, we do see them when our sun rises and sets because the lower levels of visible radiation, like red and yellow, travel further than higher levels like blue and violet; there is a greater volume of atmosphere between where we are and where the sun rises and sets so only the lower levels of visible radiation are able to reach us. On the other hand, we see a yellow sun in midday because the sun is closer to us. While the higher levels of radiation - and this includes the invisible ultraviolet part of the spectrum - have a shorter distance to travel before they can reach us, it all gets scattered by our atmosphere. The sun's intensity ensures that the lower levels of radiation directly ahead of it reaches us, and because it is longer and therefore 'thinner', it is not scattered as easily.

It should be worth mentioning that we don't see violet light in our sky - even though our sun does emit it - because that part of the radiatio spectrum is not as easily detectable to the human eye.

Upon thinking back about my planet, there are several differences that pop up. First of all, my planet's sun is not as big and not as strong as Earth's sun is. This means less visible radiation overall, are very little higher level visible radiation like blue and purple. My planet's atmosphere may or may not be thicker, and there may or may not be more atmospheric albedo. I am thinking that while the surface of the planet may be warmer, and this warmth may be more evenly distributed, there may not be as much actual light on my planet. It may mean a differently-coloured sky, maybe more of a dark cyan than a light blue. The colour of the sky might be denser, meaning you would not be able to see as far up into the sky. Imagine something along the lines of a very cloudy or somewhat overcast sky, except this would be constant and not occasional. I.e. not an indication of rain or thunder. This planet's sun would be more orange or red than yellow, and it would not be as bright. It would also not be in the sky as long as Earth's sun is. Then there is the issue of the clouds...but I am not there yet. I may need to look into that some more.

I will post an update on the table I am (trying to) create for my article once I actually get around to it. Or maybe sooner, if I come up with more research on my planet in general. In the meantime, this entry is a good example of how deep I go into the scientific aspects of my conworld so it is a good example of what to expect when I finally do get my conworld article(s) up. I will end here now. Thanks for reading.