Notes
To Open the Sky, a standalone novel by Robert Silverberg.

A fixup novel based on a series of short stories first published in Galaxy:

• Blue Fire (June 1965) – 2077 added to title in novel
• The Warriors of Light (December 1965) – 2095 added to title in novel.
• Where the Changed Ones Go (February 1966) – 2135 added to title in novel.
• Lazarus Come Forth! (April 1966) – 2152 added to title in novel.
• Open the Sky (June 1966) – To Open the Sky: 2164 in the novel.

The image opposite and the blurb below are from the 1977 printing of the Sphere Books paperback edition, ISBN 0722178271. Cover illustration by Peter Elson.

Publisher's Blurb – Lower Cover
ON 22ND CENTURY EARTH, A NEW RELIGION WAS GATHERING POWER. . . .

THE VORSTERS were the blue-robed worshippers of the atom, symbolised by the Cobalt-60 reactors that glowed blindingly on every altar in their fast-growing churches.

THE HARMONISTS were the green-robed heretics, a breakaway faction condemned as icon-adorers, who believed that their creed was truer to the code of Vorst, the Founder.

At the beginning of the 22nd century, Earth colonies were established on Mars and Venus. But the ultimate dream – to travel to the stars – was still an impossibility.

A few enlightened men believed that the Vorsters and the Harmonists could solve this seemingly insurmountable problem, if they could only forget their differences and work together. But the hatred between the two factions was too deep to be reconciled – until a conflict on Venus between a Vorster priest and his Harmonist opponent resulted in some totally unexpected developments. . . .