In addition to his other accomplishments, William Herschel is also noted for his discovery that some stars do not merely lie along the same line of sight, but are also physical companions that form binary star systems.
Selain itu William Herschel juga menemukan bahwa beberapa pasangan bintang bukanlah bintang-bintang yang secara kebetulan berada dalam satu arah garis pandang, melainkan mereka memang secara fisik berpasangan membentuk sistem bintang ganda.