We continue with planets and their gravitational effect on starship combat. This page starts off with a note that you're almost never going to have more than one planetary body on the map at once, since at the scales being used, nothing's going to get that close. On a game map, the Moon would be twenty feet from Earth. However, since turns are ten minutes long and ships can pull some very steady G's when accelerating, you might have to actually shift the planet template around on the map, just in case the ships in question decide to go elsewhere.
Further, the Sun (ours, not some other star) would be a 371-foot template to include its gravity well, and the innermost circle (representing the Sun itself) would be 70 feet in diameter. So, it's not likely that there will be combat happening around stars. Unless it's a white dwarf star, maybe. Although they still have a massive gravitational field, despite their tiny size. So, no star fights.
Asteroids can be included on the map as well, although they're just obstacles to go around; there's no gravity to worry about, even from the biggest ones. You can put about 36 asteroids in one square foot of game map, scattered around.
The rest of this page gives us stats for some 'standard' worlds (diameters ranging from 1 game inch to 10 inches), as well as the planets of the Solar System for comparison. And holy snot rockets, the gas giants will take up massive space on the game board. Jupiter will encompass over seven feet in diameter, just for the planet alone; its gravity field will extend out to almost twelve feet. So, not a lot of battling around gas giants, either. Although it might be interesting to play on a very large gameboard that can accommodate something Jupiter's size, and then have the fight around one of its moons. Because Jupiter's moons are big enough to have their own gravity; Ganymede is nearly as big as Mars.
Just for fun, I'm going to use official astronomical stats to calculate the numbers for the four main moons of Jupiter. It'll be good practice, too.
We start with Io, which has a D of 3.66 and an M of only 0.015. Well, that's not much, is it? Next is Europa, with a D of 3.12 and an M of 0.008. Tiny little thing, isn't it? Ganymede is the big boy, with a D of 5.26 and an M of 0.025. Finally, there's Callisto, with a D of 4.82 and M of 0.018. By comparison, Mercury is D of 3 and M of 0.05. Apparently, Jupiter's moons are somewhat...light. Maybe that's why they're moons and not planets. Heavy thinking, I know.
Alright, so there's not going to be much gravity, by the looks of things. But, we shall see. I'll start with Ganymede; if its numbers turn out to be negligible, I'm not going to keep going, since the rest are smaller. I will need its K number (density) as well, and that is 0.35, according to the numbers NASA has. I'll accept those as accurate.
So, there are four formulae; the first one is easy enough: R=D/2. Second is G=K(R/4). Third is M = G cubed. Wait...I have a formula to calculate that? Should have looked back a couple of pages first before doing 10 to the power of 24 calculations for mass numbers. Well, it will be interesting to see how close the formula gets to the actual. The fourth formula is the L formula, which is L = 4 * the square root of M/G.
So, entering the numbers for Ganymede in the handy spreadsheet I just put together, we get R = 2.63, G = 0.23, and M = 0.012. Not too far off from the calculation I did. Anyway, it turns out that even at the planet's surface, you're not going to get any significant gravitational effects, since Ganymede's G works out to less than 0.25. Oh, well. It was a fun little exercise.
The tables are a bit odd in one sense; M is supposed to be calculated from the third formula, but it's given in the tables for all the planets. K is needed for the formulas, but it isn't given. That's what threw me off earlier; I didn't remember the K, and the table doesn't give it to remind me. Oops.
So, that's it for tonight; another page done, and about twenty more to go in this book.
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