The Astral Burnish Dragon is a being of incredible size and power, but just how great is this size? The diameter of the Sun is 1392000km.
= 2*atan(715/(1615/tan(70/2)))
= 0.413542582 rad
= 23.6942445976015428 degrees
Enter that through the angscaler and we have a distance of 3319600km. Keep in mind too that there's even more of it, and it's bending, so it would ultimately be even longer. Infact, it could be far longer, given it then plows through all the planets of the Solar System and beyond.
Final Results
Astral Burnish Dragons' length = >3317900km
