How many letters does the top answer for “wrote rudolphine tables” have?

The most common answer is brahe (5 letters).

Crossword clue: wrote rudolphine tables

2 answers found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

brahe 5 letters wd-fact-v3

Danish astronomer whose observations of the planets provided the basis for Kepler's laws of planetary motion (1546-1601)

kepler 6 letters wd-fact-v3

German astronomer who first stated laws of planetary motion (1571-1630)

author of rudolphine tables 50% similar → brahe, kepler

wrote cards on the table 50% similar → christie

wrote the periodic table 50% similar → levi