To an astronomer, does it look like Pluto? (3,4)
I believe the answer is:
dog star
'pluto?' is the definition.
The answer and definition can be both natural objects as well as being singular nouns.
Perhaps there's a link between them I don't understand?
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for dog star that I've seen before include "Drags to find other name for Sirius" , "clearly visible shiner" , "What may not be seen on cloudy night" , "'Another name for the Sirius constellation (3,4)'" , "heavenly body?" .)