[ Closed ] The View From Planetside - Relative Sizes Calculated

At this time I'm not processing requests for relative Luminosity and Color of Stars - only relative sizes for now. Once those requests have been processed I will begin looking into the Luminosity and Color of Stars.

~Robert

Correct, although parallax relies on vast distances to acquire its accuracy and requires two "stationary" and one mobile object that revolves around only one of the former objects as references. Also the celestial body to which you are making your parallax measurement cannot orbit your mobile object nor the stationary object about which your mobile object revolves. We typically use Earth and the Sun for our parallax measures to other stars and the assumed distance of 1 AU between Earth and the Sun. Also parallax requires two measurements and it takes a half of a revolution about the sun to acquire each (although I have no doubts that with some high-end expensive technology you can acquire measures in a smaller time frame - but parallax can be done on the cheap without any technology invented in the last 2000 years by waiting a half of a revolution).

But because parallax is only useful for vast distances at least tens of thousands times longer than a star system is wide and has very particular needs regarding its three points of reference, parallax can't possibly be used in determining relative sizes of celestial bodies within the star system they are being made from.

Both my method, Parallax, and one other (false) method were the contents of my presentation and thesis and the pros and cons of each were discussed along with their validity (or lack thereof). Keep in mind I was presenting this to a Mathematical community so proof was of higher value and thus most of my work went into exploring how parallax works, and such.

My method isn't really "mine" though, it's an astrophysics spin on an old method of indirect measurement. My favorite method however is "dissimilar triangles" (that always gets a "huh?" out of my fellow Mathematicians). Not going to toot my own horn very loudly but I put everyone in one of my math classes to shame with that method on one occasion, laying waste to the supposedly superior method of similar triangles. The idea is to have a low error margin and to know which method minimizes your error margin the most given the circumstances.

~Robert

Thanks again for all your work on this, Robert, it really is awe inspiring.

Jason, can I request these images get uploaded to the wiki as Robert posts them in the RPE?

Silent, thanks for posting the updated Verse in Numbers. I came across it a few days after linking to the original and hadn't got around to updating here.

Ash

I figure some people are curious to see what it is I do to get my results. So here's a snapshot of my work on Santo's moons. Basically I create a planet, the Earth's Moon, and all the other moons for the planet in question. I set the distances (from the observer not the planet - the effect this has on the distance is factored in), set the radius of each moon, setup the lines tangent to the moon that pass through the observer's points, and then have the program calculate the angular measure between the tangents. Then I just create circles for the Moon, and each of the planet's moons with a radius set as a scalar multiple of the magnitude of the angle. And...presto! Perfectly proportionate moons based on TVIN 2.0! 

Of course it's important to observe that the relative sizes are closest to actual when comparing the high-noon positions of each. If one is at high noon and another is not, the relative sizes are (slightly) different, but if each were at high-noon then my diagrams are precise. :-)

Side Note: You'll notice I have the moons shifted in such a way that they are closer to the planet than the actual distance (as mentioned I set the distance from the observer) - this doesn't throw off the numbers at all, but the reason I shifted them is so I can see what I'm doing more clearly!

~Robert

Last edited by RLongtin (2012-02-21 19:59:46)

Noted about adding this to the wiki.

Just also wanted to say, this assumes standard orbit of those moons (unless the dataset you are using also has elliptical information for the orbits? I don't recall TVIN having that. That would be insane if it did!)

I've started work on the stars though giving some thought to it, I've decided something.

Rather than continue to do this bit by bit, I'm going to do a full construction of The 'Verse in Geogebra instead. It will be a fairly large project overall but the results will be well worth it I think. 

~Robert

Coooool. 

Deborah

*So* looking forward to it, Robert! Perhaps compartmentalise it, just do a little at a time?

Ash

Yuck, hope things get better soon!