Double Stars Card

Adapted from Camille Flammarion’s classic The Marvels of the Heavens (1870). While double stars often occur as binary pairs (two stars bound in gravitational orbit with one another) they can also form optical doubles, whereby two stars at great distance from one another align by chance in the line of sight of the observer. Multiple stars (three or more) are classed in the same way as doubles. Image courtesy The Library of Congress.

Printed on acid free paper.
Measurements: 17 cm x 12 cm.
Comes with 120gsm recycled envelope.
Blank inside.