I'm into amature rocketry. To determine accurate altitude of a rocket sent up into the sky you need one of two things, an altimeter on the rocket itself, or two seperate points to accurately measure from, such as the ground and a skyscraper. There is no way to send an altimeter to something as distant as anything we're talking about, so forget that idea. But getting into trig, you must have two spaced, uncommon-dimensional points to accurately measure a distant object. Okay, hypothetically, you send a rocket up into the sky about 600 feet, if you are standing next to the launchpad, you can only "triangle-measure" until a certain unnamed altitude where the measurements become to close and cause static and VERY possible measurement error. Now say we propose your theory to this equation. I stand next to the launchpad and use binoculars to see the rocket. Even if the rocket stayed stuck in the air at it's highest climax, standing next to the launchpad, there will always be static and possible error. You must find another distant place to measure from and then put the measurements together to find an accurate measurement. For measuring distant celestial figures, this 2nd point would probably need to be another planet possibly in another solar system.