Astronomy: Biographies
- Jan Hendrik Oort
- Jean Picard
- Jeremiah Horrocks
- Jeremy Brett
- Johann Elert Bode
- Johann Franz Encke
- Johann Gottfried Galle
- Johann Tobias Mayer
- Johannes Georg Hagen
- Johannes Hevelius
- Johannes Kepler
- Johannes Muller
- John Couch Adams
- John Flamsteed
- Joseph von Fraunhofer
- Maria Mitchell
- Martin Sir Ryle
- Nevil Maskelyne
- Nicholas Copernicus
- Nicolas Camille Flammarion