George Ion

I think i found it. It was in... Wikipedia. However, when i tried to use it, i saw d is on both sides of the equation.

I got the same thing on the last link in my initial post, but center to center. What i need is center to center (no specific location on Earth surface), daily . I have a data set with with 5424 eqs > 4 in Greece since 1940 (yes it is a very important seismic area, probably most active in Europe). I cannot possibly go in there to fill that data manually and on the given link there's only apogees and perigees. The only way to do it is a formula derived from Moons ecliptic which i think i have figured as i said in my first reply. Things would be much more interesting with location, but it is not part of the same equation. The Earth surface acceleration component follows a law of Earth rotation against self, it varies on a 24 hours cycle and it cold be biggest around the time Moon is at zenith and would vary with latitude, Moon plane inclination, etc.. Much more complicated. I was looking yesterday for John Walker's email and found out he was dead. But this can't be done in a spreadsheet LOL. This is where the big boys with supercomputers with AI and vocal interface should step in. Hard to believe they didn't figure it yet.

I think i got it all figured out. Since Moon orbit eccentricity is about 5% i think for the purpose of establishing a correlation only, i can approximate and say the angular speed is constant in which case i can use this figure and subsequent formula. I would appreciate for anything better than this that would be manageable in a spreadsheet.

I once (8 years ago) built a table with correlation between moon phases and distances with earthquakes in a certain seismic area. Can't remember where i took the moon distance from, but i would assume from a calculator on a site. It seems there is a strong correlation with moon distance. I need to populate a table with distances to the moon on certain days to verify it again with a different data set. Distance could be the distance between the center of the two bodies, no need for distance from a certain pair of coordinates and it can be at midday. If there is a formula that i can put in a spreadsheet. It can be a two body only periodic simplified formula, no need for other factors. One option would be to do it with Stellarium, but i have to input coordinates and would be time consuming. Or is there a formula that i can put in a spreadsheet that can call a Stellarium (or a function on a site) to return the moon distance for a certain parameters. Like this site gives only perigees and apogees, but i assume it uses a formula.