Beta Monocerotis (Beta Mon, β Monocerotis, β Mon) is a triple star system in the constellation of Monoceros. To the naked eye, it appears as a single star with an apparent visual magnitude of approximately 3.74, making it the brightest visible star in the constellation. A telescope shows a curved line of three pale blue stars (or pale yellow stars, depending on the scope's focus). William Herschel who discovered it in 1781 commented that it is "one of the most beautiful sights in the heavens". The star system consists of three Be stars, β Monocerotis A, β Monocerotis B, and β Monocerotis C. There is also an additional visual companion star that is probably not physically close to the other three stars.