Abd Al-Rahman Al Sufi
Abraham bar Hiyya
Adam Riess
Adriaan Blaauw
Adriaan van Maanen
Al Battani
Alan Harvey Guth
Albategnius
Alex Filippenko
Alexander A. Gurshtein
Alexander Dalgarno
Alexis Bouvard
Alfred Bohrmann
Alfred Fowler
Ali Qushji
Allan Rex Sandage
Alyssa A. Goodman
Amédée Mouchez
Amy Mainzer
Anders Jonas Ångström
Andre Louis Danjon
Andrew Ainslie Common
Andrew Fraknoi
Angelo Secchi
Anneila Sargent
Annibale de Gasparis
Annie Jump Cannon
Anton Pannekoek
Antonia Maury
Antonio Abetti
Aristarchus of Samos
Arno Penzias
Arthur Auwers
Aryabhata
Arzachel
Asaph Hall
August Ferdinand Möbius
Auguste Charlois
Avi Loeb
Axel Firsoff