Anton
Pannekoek

Amsterdam




Jan
Woltjer

Leiden (Astronomy Tree)


David
Gill

Royal Observatory at Cape of Good Hope (Astronomy Tree)












Wilhelm Friedrich
Ostwald

Leipzig University (Chemistry Tree)


Hans Emil
Lau

Urania observatory, Copenhagen


Elis
Strömgren

Copenhagen University


Karl
Schwarzschild

Astrophysical Observatory Potsdam




Edward Emerson
Barnard

Lick Obsrvatory (Astronomy Tree)


Edward Singleton
Holden

Lick Observatory (Astronomy Tree)


William Wallace
Campbell

Lick Observatory


Robert Grant
Aitken

Lick Observatory (Astronomy Tree)


Gerard P.
Kuiper

University of Arizona


Carl
Sagan

Cornell

Christopher Frank
Chyba

Princeton
(Options)

Kevin P.
Hand

Stanford (Chemistry Tree)

Christopher ChybaX