Can Excel accurately calculate planet positions in real-time?

[Silverbug]

Hi All,

I wanted to see if it were conceivable to create a spreadsheet you could calculate the position of planets within our solar system given a lat and long position and using the current time?

I've tried searching for something similar, or formulas to calculate these, but haven't had much luck. perhaps I'm just not looking for the right thing.

I eventually want to be able to create something in php, but figured getting it in Excel to start with may be a better way of approaching it.

Any help or suggestions would be hugely appreciated.

 

[Bandersnatch]

What you're looking for is called "ephemeris"(pl. ephemerides).
You can find both astronomical and astrological ephemerides on the net. Shockingly, the latter ones are not necessarily complete bollocks, but might use some weird coordinate system.

Here's a couple of sites for finding (astronomical)ephemerides:
http://ssd.jpl.nasa.gov/horizons.cgi
http://www.aphayes.pwp.blueyonder.co.uk/ephemeris/index.html

And here's a guide on how to calculate planetary positions as used by the second one of the tools linked above:
http://www.stjarnhimlen.se/comp/ppcomp.html

Whether it's doable in spreadsheets is a different kettle of fish.

 

[Silverbug]

thanks Bandersnatch, really appreciate the help and explanation i'll have a look through these sites and give it a go :)

 

[Silverbug]

I've had a look at the last link in there and can't figure out why when I input the formula I get slightly different values. I don't believe it rounding issues as the variance is too large.

 

[Philosophaie]

The formulas are correct.

It is just that data from JPL Horizons is actual data measures from the Barycenter Model and the data calculated my not be as accurate.

Try more accurate data:

http://ssd.jpl.nasa.gov/?planet_pos

Look at links on the bottom.