Assertion: period comet | /r/HasProperty | difficult to detect
Facets:
Source sentences:
text: Since the threat from long-period NECs is estimated to be at most 1% of the threat from NEAs, and long-period comets are very faint and thus difficult to detect at large distances from the Sun, Spaceguard efforts consistently focused on asteroids and short-period comets.
text: Since the threat from long-period NECs is estimated to be at most 1% of the threat from NEAs, and long-period comets are very faint and thus difficult to detect at large distances from the Sun, Spaceguard efforts consistently focused on asteroids and short-period comets.