Was standing at back door waiting for dogs in garden. Area is a 'dark sky park', so little air traffic and not light polluted. Star like aircraft that briefly shone beam and stayed parallel with an aircraft who was flying directly over me. Checked flight radar which showed jet but nothing else. Over within two mins maximum. Object was clearly not an airliner and did not emit any noticeable sound. Very smooth in its flight pattern. Object disappeared from view due to my living on steep hillside, so over hill.