“What is an astronomer?”/“A night watchman with a college education.”

If an astronomer watches the night skies, does that make him a night watchman? A riddle has been cited in print since at least 1986:
 
Q: What is an astronomer?
A: A night watchman with a college education.
 
       
Google Books
Einstein Anderson Makes Up for Lost Time
By Seymour Simon
Illustrated by Fred Winkowski
New York, NY: Puffin Books
1986
Pg. 42:
“Are you thinking of becoming an astronomer?” he asked.
 
“I might,” Einstein said. “Of course you know that an astronomer is a night watchman with a college education,” he continued. “
     
Google Books
The Science Zone:
Jokes, Riddles, Tongue Twisters & Daffynitions
By Gary Chmielewski
Chicago, IL Norwood House Press
2008
Pg. 4:
ASTRONOMER
Night watchman with a college education.
 
Twitter
Bollywood Sargam‏
@bollywoodsargam
Space jokes - 8785 Joke: What is an astronomer? A night watchman with a college education. .... http://tinyurl.com/quetd8
9:04 AM - 21 May 2009
   
Twitter
Morten Stenbaek‏
@mobitwix
What is an astronomer?A night watchman with a college education.
2:15 AM - 22 Dec 2009
   
Google Books
The Mammoth Book of Really Silly Jokes:
Humour for the whole family
By Geoff Tibballs
London, UK: Constable & Robinson Ltd
2011
Pg. 313:
What is an astronomer?
A night watchman with a college education.
 
Google Books
Sensible Nonsense.. Frank’s Comic Pack:
Humour Pack Series
By Frank Paul
BookBaby
2014
Pg. ?:
What is an astronomer? A night watchman with a college education.
 
Twitter
Lucky Score‏
@LuckyScoreNet
What is an astronomer?
A night watchman with
a college education.
#Joke from #SpaceJokes in #Jokes, #Humor and #Satire
9:34 PM - 29 Dec 2017