A double star in which the components orbit a common centre of gravity and are gravitationally bound to each other. Many stars in the Galaxy and the Universe are binary stars.

Sirius the brightest star in the night-time sky is a binary star. It's companion is a faint white dwarf (credit:- Fred Espenak)

Glossary A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Sky Highlights - April 2017

Shop at Amazon US

Shop at Amazon US

Current Moon Phase



If you like the website and want to contribute to the running costs then please do so below. All contributions are most welcome.

PayPal - The safer, easier way to pay online.