The Orb in the Sky, more commonly known as "the comet" or "the fourth moon", is a strange celestial body that first appeared in The Brightest Night as Sunny and Clay flew over the MudWing army encampment. Sunny describes it as the appearance of a fourth moon, making another brightest night, "even though there should not have been another for ninety-four more years." She also sees it to be an omen with spiritual meaning.
The Orb is formed out of skyfire, a rock that can block a mind reader's telepathic abilities. The earth shook moderately when it appeared, and Starflight claimed that the orb is the cause of these earthquakes and is most likely a comet or meteor.
These earthquakes broke the enchanted bracelet that Darkstalker was wearing, and freed him of his eternal slumber. Fatespeaker also predicted that the Orb was going to crush them all, though no one believed her, especially after the Orb passed them by safely. However, she later "predicted" that it would come back. However, the sky fire passed through Palm's head, which killed her, as confirmed by her daughter Onyx.
The orb in the sky was visible for about a month around the false brightest night. Its passing was accompanied by the earth shuddering. At the end of the book, Fatespeaker "predicted" it would crash into Pyrrhia, killing all the dragons, but this wasn't true.
Pieces of orb in the sky had fallen from the sky and were called skyfire. This material blocks the abilities of a NightWing telepathy, hence, when Onyx and Turtle wore it, neither Moonwatcher nor Darkstalker could read their minds. When Moon held it, she couldn't read minds, and Darkstalker couldn't read Moon's mind or talk to her. Onyx and Turtle both had pieces of this rock at the beginning of the book, and Winter, Kinkajou, and Qibli were given some at the end so that Moonwatcher didn't have to read their minds.
The comet later disappeared, leaving no trace of its appearance. See Pyrrhia for more information.
From the book:
Also known as the last page.