\(\def\|{&}\)
The description of the word you requested from the astronomical dictionary is given below.
From the VSOP model (Variations Séculaires des Orbites Planétaires) of P. Bretagnon and G. Francou, the positions of the planets can be calculated very accurately for a few thousand years into the past and into the future. This model is available for free. See //adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1988A%26A...202..309B&db_key=AST&data_type=HTML.