# How to determine the formula to calculate this position of reflected Sun?

I created a geometrical simulation of how the Sun is reflected on a wall along the day and along the year, using Geogebra:

https://www.geogebra.org/classic/dckhbc8h

Playing with parameters, I found an oddity: in some specific cases, changing the "season angle", i.e. inclination of su circle w.r.t. horizon, I can see the "sun reflection line" always passing in same point on the wall along whole year:

Overlapped:

Is this a real behaviour or just an error in my simulation?

Does it happens always at same time of the ay? My simulation currently does not show the times along the "sunLine" segment.

How could I build a Geogebra formula to directly draw the "convergence point" of all the sunLine lines along the year?

• Somewhat close to my recent question Math behind a heliostat, I think. Maybe you could help me with mine, please? I never heard of GeoGebra before, so it looks it could be easy for you? Apr 6, 2021 at 16:27
• Yes, I already have a ready-made source code for an heliostat, I wrote it some years ago: jumpjack.wixsite.com/progetti/sorgenti-ipsun Apr 6, 2021 at 18:38