Talk:Zebia
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Discussion on the size of Zebia:
[quote="Tmeister"] Obviously the planet cannot be exactly the same size as Earth (~ 3960 miles or 6372 km as the radius), but in light of the discussion about the size of the planet, it needn't be significantly larger. So how about around 4100 miles (6600 km)? The increase in gravity is very low - if the density is comparable to Earth's, an object weighing 50 pounds on Earth would weigh 51.8 pounds on the new planet. On the other hand, this gains an extra 4,513,600 sq miles of surface area (11,690,170 sq. km, about 68% of Russia, admittedly not very much).[/quote]
I don't know how you got this answer, I arrive at a different one.
If r is the mean radius of thre Earth, and x is the difference between Zebia's and the Earth's radius, then the new surface area is 4п(r+x)^2 = 4п(r^2 + 2rx + x^2). Since we want the increase in surface area only, we subtract the Earth's actual surface area, and the resulting difference can be calculated (at r=6372 and x=228):
4п(2rx+x^2) = 4п(2,906,000 + 52,000) [rounding off the thousands]
= 4п(2,958,000)
= 37,152,000 sq.km.
This is more than 1.5 times the area of the ex-USSR.
Nevertheless, I would be in favour of making the planet even larger - or, alternatively, quite a bit smaller - then the Earth. Adding 228 km to the actual radius of the Earth adds only about 3% - this, to me, is too much of a coincidence. Let's make it a good 15% more (or less). I suggest, more - making a radius of, say, 7350 km. This should certainly give us a large enough surface area to play on. (If heavier gravity becomes a problem, we can always decrease the average density of the planet - as a general principle in conworlding, always vary the parameters you know the least about So, what's the increased surface area now, with an x value of (at r=6372 and x=978):
4п(2rx+x^2) = 4п(12,464,000 + 956,000) [rounding off the thousands]
= 4п(13,420,000) = 168,555,000 sq.km.
This is slightly more than the actual total land area of the Earth (roughly 150,000,000 sq.km.), so that by applying our 15% or so increase in the radius, we can double the land area and still have about 20,000,000 sq.km left over as more oceans.
Let's wait and see what others think.
Gsandi 02:07, 26 February 2007 (PST)
