| Answer | Crossword Clue |
|---|---|
| COPERNICUS | Pioneer in astronomy, c. 1530. |
| astrolabe | astronomical instrument for taking the altitude of the sun or stars and for the solution of other problems in astronomy and navigation: used by Greek astronomers from about 200 b.c. and by Arab astronomers from the Middle Ages until superseded by the sext |
| LINNAEUS | Pioneer in systematic botany, c. 1750. |
| ARCHIMEDES | Pioneer in physics, c. 250 B.C. |
