In my worldbuilding series, I explained the physics of worldbuilding and how to create your own solar system. Today let’s examine an example of this process. To aid with this, I’ll show the spreadsheet I use in order to help me calculate the parameters of my planet and it’s sun.
Revision 3: Star Systems Template
When you open the template, you’ll notice I have a section for constants, for the star, for the habitable planet, and for any moons that planet may have. As a warning: do not delete Earth’s row or any of the constants. Most of the equations rely on both in order to function properly. I’ve given space for you to create your own stars and planets (and you can edit the examples to the parameters you want as well). The moon section of the template is more experimental, and I offer it as a guide as to what to expect in regards to the tidal effect moons have on a terrestrial planet. Also, this spreadsheet is modeled for terrestrial planets. You can use it to compute a gas giant, but the columns that describe the horizon distance would not be applicable to gas giants (as they have no actual surface) and in the moon section only the Roche’s limit is applicable. (The tidal effects of the gas giant on your moon is not included in this spreadsheet).
Please see my world-building series for information on how to build your solar system; I explain the physics of it there. The template is just a resource to help you calculate the astronomical parameters for your planet and its star. If you read through my world building series with the template on hand, it’ll help you understand each section of the template and the science behind those calculations and parameters. Plus, you’ll be able to build your planet as you go! It’ll be fun, so give it a try.
For the planet section, you will be comparing it to Earth in terms of its radius, mass, and density. This is to help you visualize your planet; also, for the semimajor axis, place it within the habitable zone computed in the star section; if you don’t, then your planet won’t be able to harbor life. Also, the advantage to comparing it to earth is because you know what Earth is like; by making this comparison, you’ll able to better visualize what to expect on your planet. To make it easy for you, I labeled the factors that you have to determine yourself, and the other columns will calculate the parameters based on what you decided. Feel free to experiment a bit with the examples I provided. I’m offering this template as is, and I’ll answer questions about the science behind it, but I am not going to answer questions on how to work Microsoft Excel (or Open Office Calc).
As this is an ongoing project, I may update the spreadsheet from time to time, and I’ll always list the revision number along with the updated spreadsheet.
I hope this resource is useful to you all, and feel free to comment with suggestions or questions.