A ring of gas, plasma, dust or particles surrounding a celestial body such as a star or a black hole. Accretion disks are involved in the formation of stars and planets. They also source powerful radiation emissions from objects such as quasars and radio galaxies.

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

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Current Moon Phase

CURRENT MOON

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