Astronomical Dictionary on Letter #B

Binary Star

A double star; most commonly, a physical binary, or two stars which revolve about a common center of...

Blue Moon

The second full moon in a calendar month, or the third full moon in a season containing four....

Breccia

Coarse-grained rock composed of angular fragments of pre-existing rock....

Bedrock

Continuous solid rock that underlies regolith and is exposed at outcrops....

Basin

A depressed area with no surface outlet....

Basalt

Fine-grained igneous rock (rich in mafic minerals) that has erupted onto the surface....