Assertion: telescope's tube | /r/HasProperty | open
Facets:
value: in newtonian telescopes
type: LOCATION
value: at one end
type: LOCATION
value: to the air
type: TRANSITIVE-OBJECT
Source sentences:
text: The tube is open to the air, which means dust on the optics even if the tube is kept under wraps
text: In Newtonian telescopes, the tube is open at one end.