Celestia Forums

...and the ones that hit the Moon probably are in amongst the craters somewhere :) It would be kinda cool if we did someday find an asteroid that had the same composition as the Earth or Moon though :) But that's what I'm talking about. The Moon is more heavily cratered than Mercury. Are the excess...

Is it possible that an analytical solution for the N-body problem does exist, but has thus far eluded our brightest mathamaticians? Or has it been proven that an analytic solution can not exist?

Rings are moons. Just lots and lots of little ones. And they have to follow the same orbital dynamics as a larger moon. The important thing here is the Hill Sphere, or the sphere of influence, must be stable over long time-scales. Our Apollo spacecraft had an easy time orbiting the Moon. A proposed ...

I do have that book! In fact it's an Amazon link on my Gravity Simulator webpage. If anybody buys it through my link I earn a couple of bucks. So far... no purchases :x . But I can't find the formula in there. Most of the math in that book is over my head anyway 8O . An example of "over my head": Fo...

Uranus and Neptune are just one of many theories. I'm not sure I agree with it, but that might be because I don't completely understand it :oops: . Neptune, especially is thrown into lots of theories. But I'm not talking about moonlets orbiting the Moon. I'm talking about moonlets getting ejected in...

Does anyone know the formula to compute orbital velocity of a circular orbit when the orbiting body is not considered a massless particle? Using the formulas for circular orbital velocity of a massless or nearly massless particle compared to the primary (such as a spaceship) does not give good resul...

Let me throw in something I've always wondered about. When the debris from the collision of proto-Earth / Mars-sized thing was in orbit, forming the Moon, it probably formed many small moonlets first that later gathered into bigger moons, and utlimately one moon. But as the current Moon was almost f...

Chiron will pass 203,000,000 from Saturn in 2242, 177,000,000 in 2488, & 167,000,000 in 2833. I don't think Chiron's orbit is known well enough to predict much further into the future. All these passes alter Chiron's orbit noticably. Chiron even becomes both a Uranus-crosser and a Saturn-crosser at ...

The Day equation above should do that without modification. To avoid an acos crash, you could first evaluate the expression within the acos brackets of the Day equation: if it is >1 or <-1, branch to calculate FullDaylight; if it's a valid cosine, calculate Day. (Sorry, you've probably got all that...

Your formulas seem to work quite well. Here's an updated calculator. The only thing it fails to do is compute day / night for artic regions that are not in their full daylight or full night period. I'll mess with that later. http://orbitsimulator.com/celestia/Project1.exe http://orbitsimulator.com/c...

Hi Tony: Nice calculator. Can I suggest: 1) Changing that first label to "Solar Day" to avoid perpetuating my dumb mixed terminology 2) Maybe trap the situation where lat > 90-tilt, and then force MinDay = 0 and MaxDay = d, to avoid crashing your cos function. Grant Done! Thanks Grant New source: P...

I get better results with Grant's formula by comparing with data from http://www.srrb.noaa.gov/highlights/sunrise/sunrise.html It only differed by a few minutes, which can be explained if their calculations don't use point mass and if refraction is included. I suck at entering numbers into a calcula...

There's more inputs needed. The eccentricity of your planet's orbit will have an effect. Earth's eccentricity causes sundials to run as much as 15 minutes fast during certain times of the year. So will the shape of your planet, specifically the magnitude of the equatorial buldge (although its not ve...

...has a bunch of liquid material on it (carbons, methane, whatever) what happens if the Huygens probe has the unfortunate luck to take a dunk? (sorry if this has been brought up before) It's designed to float! In fact, the percentage of the part under liquid, and above liquid will tell scientists ...

Thanks, Chris and Grant. The formulas in Chris' link might do the trick for me. Grant, your formulas would be useful to check whether or not I've programmed it correctly. But that's months off since I don't have much time at the moment, so I'll ask you then.

Does anyone know the formulas to compute gravitational force at a given distance for a non-spherical object? Something orbiting an oblate object will probably be pulled in a slightly different direction than the true center of mass some of the time. I imagine that the further away from the oblate ob...

8 inches is a good telescope. What brandof telescope do you have? (Meade, Celestron, etc.) And what type of model, (dob, s-c, etc.) and is it computer controlled? Don't forget the Andromeda galaxy. It's an easy find for an 8-inch scope. Under a dark sky, it's a naked-eye object. There are still 2 co...

Your eclipse example is a good one. I was in Arizona in 1994? for an annular eclipse. We arrived at a campground near the centerline, and I saw a bunch of people with cameras and zoom lenses. But when I asked where were their solar filters they gave me a puzzled look. These people were not here for ...

You'd have no problem on Europa viewing your surrounings with the naked eye. Europa receives 4% of the sunlight that Earth receives, but 4% of the Sun is still a very bright light. On Earth, you pupil turns into a small dot on a bright sunny day. On Europa your pupil would open wide and compensate f...

Sunlight at Saturn would be much brighter than a full moon. I've heard that a full moon is about 1/400,000 as bright as the Sun. Here's the brightnesses of the planets: Mars ~ 1.5 au: 1/(1.5*1.5) = 0.44 * the brightness of Earth Jupiter ~ 5 au: 1/(5*5) = 0.04 Saturn ~10 au = 0.01 Uranus ~ 20 au = 0....