To answer How to calculate conjunctions of 2 planets earlier, I computed all planetary conjunctions from -13200 to 17190 and you can search the results at:
Prefilled with the values you want (assuming two fingerwidths is 2.5 degrees):
How often do Venus and Saturn come together in the sky like this?
Sagittarius is between November 22 and December 22 (2019, UT1).
The "List of conjunctions (astronomy)" (2015-2020) says that they have had conjunctions on:
Date Time UTC Planet Angle distance Planet Elongation to Sun
January 9, 2016 &...
The black hole shadow is basically the image of the event horizon. As you know the event horizon is the geometric locus of the points from which a light ray pointing in the opposite side of the singularity (the center of the black hole) can't no longer escape from it. Any other light ray emmited in any other direction from those points would never reach an ...