I'll justify my diagram just a bit more, maybe for a clarification. True, the sun has a diameter much larger than earth.
My reasoning for the sizes shown was that even if the sun is much larger, the earth appears to be much bigger by virtue of being much closer. My diagram makes some bad assumptions, such as if the center of the sun is below the horizon, then you don't see any of the sun. This assumption is okay for most times of the night, when you can't see the sun from most airplane-reachable altitudes. My argument could very well break down if one were to start dealing with space. It also doesn't work terribly well if you want to realistically simulate being able to partially view the sun. A possible "solve" to that is to draw the sun first, then draw an undetailed surface (possibly curving it to follow the earth). This surface hides the sun where it isn't visible, then just lay down the detailed surface over that. Again, I'm not exactly an expert at simulations, so take this stuff with a grain of salt.
I also assumed that the sun, in FG's case, is modeled as a plain circle or sphere on the sky dome, and not as a 870,000 mile diameter sphere at 93,000,000 miles distance. Thus, it seems reasonable to me to possibly show the sun as being smaller than earth.
As for eclipses, I imagine you'd see them, even if they were beyond the horizon. =P
JD
Jonathan Richards wrote:
On Thursday 27 Nov 2003 5:23 am, JD Fenech wrote:
Not too shabby, but it probably has holes. I do know that the last time I checked, FG will display the sun at midnight, especially if you fly up high enough, even if the earth is actually in the way, as in directly in the way.
The diagram looks wrong to me. Although the sun is 93 million miles away, it is *much* larger than the Earth, so the Earth's shadow is a cone tapering *away* from the Sun. I'm not sure if this damages JD's argument about detecting Sun visibility for sensible aircraft altitudes (the atmosphere is a very thin skin around the planet) but if the sim were ever extended to spacecraft, we'd want to get the geometry exactly right.
Maybe I'll fire up FG for August 1999 and see if it does solar eclipses :¬)
Jonathan
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