Standing in backyard, smoking cigarette, looking at sky right after sun set, approximately 7:10 pm central time in santa rosa beach florida. saw a fluorescent aqua-neon green colored chevron shaped object flying very low at an incredibly fast speed. observed for 3 solid seconds, enough to almost astonish, and watched its trajectory until i lost line of sight behind tall neighboring house. waited a split second to recover my view but nothing was there. no disintegration, evaporation, or trail. this object was definitely a solid shape, not a laser, and was traveling fast enough to break the sound barrier, but i heard no sonic boom. i went back inside with a little crawly feeling in the spine and spoke to my parents about the sighting. father is in aviation and having a lot of trouble explaining away what i saw. pretty hard rational skeptic and found myself almost defensive about my observations to them. never seen anything like this before.