SOHO 342p used to be visible on Jan 3, 6 BC, now it isn't, but I found it again on Oct 7, 7 BC. How accurate is the software in regards to comets that long ago?
Thanks.
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Keiron Smith Hi Corey,
ccuracy in astronomical calculations is a tricky thing. There are a lot of competing factors and it's often difficult to know how right or wrong you are, because you can't go back in time to test your calculations. We've done our best to be accurate in our calculations, but things in the heavens aren't as clockwork as you might believe.
One major contributor to the accuracy (or lack thereof) of any historical astronomical calculation is the value of "Delta - T" you use. Delta - T is a complicated thing, but to summarize, it's the x-factor that takes into account all of the small things that can speed up and slow down Earth's rotation, and hence change the "time".The Wikipedia entry is pretty good:So, the best thing we can do is to try to match up what is displayed in Starry Night with actual recoded astronomical events, like eclipses, which seem pretty good.
Starry Night has been used for "Archeoastronomy" before and has been found by many people to be accurate, matching up with e.g. precisely measured eclipses and other events far into the past. That being said, nothing can be %100 accurate, computers are only as good as the models they use and we're doing our position calculations in "real time" in order to present a smooth, "movie like" quality. If you want extremely precise calculations for a given planet, I'd encourage you to use Starry Night as a primary source, then use NASAs JPL Planetary Ephemerides calculator to get precise positions (and also check USNO). It's more complicated, requiring a better understanding of Astronomy, but you'll get more precise (and perhaps more accurate) results.
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