# If I know apparent planetary positions how do I calculate the date?

I have planetary position in retrograde how do I calculate the date?

For eg, I know Mars was in retrograde in Scorpion (Sidereal 210 to 240 deg), how do I calculate the date and year of this?

As of now the only other info I have is that just days before this was a lunar eclipse where Sun was in Libra.

Just a year or two before this Mars was in retrograde in first half of Leo and at this time Jupiter was placed at Capricorn. These are all sidereal observations.

P.S: This is regarding an ancient scripture citation where it was said Mars was in retrograde in Scorpion, current proposed dates range from 500 BC to 6000 BC. This is all the information I have, that Mars was is in retrograde in sidereal scorpion and I want to find possible date of this happening. The iterative approach would take too long, because the span is about thousands of years

• Please be a bit more elaborate on the details and background of your problem. Otherwise a similarily fleshed-out answer would be use the known ephemeris and do an iterative search. Good guide: put as much detail in your question, showing the research you did yourself as you expect in an answer Commented Jul 9, 2020 at 11:30
• @planetmaker thank you for your comment. This is all the information I have, that Mars was is in retrograde in sidereal scorpion and I want to find possible date of this happening. I tried the iterative approach and couldn't find it, because the span could be about thousands of years.
– user34422
Commented Jul 9, 2020 at 11:40
• You have more information :) What is the accuracy you expect and the one of your input data? What's their source? What is the permissible time span, thus what do you try to (dis)prove? Something archeological? Futuristic? Have the dinosaurs seen it? How did you try the iterative approach? And why is it a problem to iterate over thousands of years? Commented Jul 9, 2020 at 11:52
• @planetmaker oh ok, I will update those things
– user34422
Commented Jul 9, 2020 at 12:56
• Commented Jul 9, 2020 at 13:35