Conversation so far:
Where did Matthew Fontaine Maury grow up?
He was born in 1806 in Spotsylvania County, Virginia, near Fredericksburg.
Did Matthew Fontaine Maury's family stay in Spotsylvania County, Virginia?
The family moved to Franklin, Tennessee, when he was five.
How or when did Matthew Fontaine Maury become interested in astronomy or the ocean?
Maury joined the Navy as a midshipman. Almost immediately, Maury began to study the seas and to record methods of navigation.

Question: What made him interested in astronomy?
Self-contained rewrite: What made Matthew Fontaine Maury interested in astronomy?