For instance , comet Hale - Bopp was last seen in 2013 at magnitude 24 .
For instance , comet Hale - Bopp was last continues to fade , making it invisible to all but the most powerful telescopes .
For instance , comet Hale - Bopp was last seen in 2013 at magnitude 24 and continues to fade , making it invisible to all but the most powerful telescopes .