Answer:

ASTR

AnswerCrossword Clue
ASTRCopernicus' sci.
ASTRStar (comb. Form)
ASTRSubj. for Neil deGrasse Tyson
ASTRSci. of Copernicus
ASTRHipparchus, e.g.: Abbr.
ASTRSagan's sci.
ASTRSci. of the stars
ASTRCopernicus's sci.
ASTRGalileo's sci.
ASTRSagan's subj.
ASTRStar sci.
ASTRTycho Brahe's sci.
ASTRCelestial sci.
ASTRHalley's sci.
ASTRStudy of the stars (abbr.)
ASTRSubj. for Carl Sagan
ASTRStargazers' sci.
ASTRGalileo's subj.
ASTRColl. major involving an observatory
ASTRSolar system sci.
ASTRSci. subject
ASTRPtolemaic sci.
ASTRSpace sci.
ASTRSolar-system sci.
ASTRCelestial prefix
ASTRStudy of the stars: Abbr.
ASTRA science: Abbr.
ASTRScience of the stars: Abbr.
ASTRCollege course: Abbr.
ASTRNatural science: Abbr.
ASTRStar man: Abbr.
ASTRScientist: Abbr.
ASTRMan at Palomar: Abbr.
ASTRStargazing: Abbr.
ASTRImportant science: Abbr.
ASTRShapley's field: Abbr.
ASTRScience course: Abbr.
ASTRThe heavens: Prefix.
ASTRHeavens: Prefix
ASTRMan with a telescope: Abbr.