Constellation

A constellation was an arrangement of stars in Realmspace as viewed in the night sky.

Significance
Clergy of Mystra, goddess of magic, held a regular ceremony in which they observed various stars and constellations, named them, and gave them reverence. Sometimes a silent image illusion was used to brighten stars and animate constellations, though this was a bit ostentatious. The Temple of Mystra in Wheloon did this every clear night in 1374 DR.

They had a reason to do so: alignments of constellations in the heavens above gave magical power to similar events in the world below.

In Kara-Tur, it was believed that the Moon Women of the Celestial Bureaucracy were responsible for steering the motions of the constellations along their courses.

History
A conjunction of certain constellations (or "heavenly signals") over Kara-Tur in heralded the birth of H'Dang Li, future first High Lord of Oceans of Tabot.

The Centaur and the Woman Warrior came into full alignment, their swords crossing, in the summer of the Year of Shadows, 1358 DR, in the evening as Waterdeep experienced the hottest day of the year. Meanwhile, unaware, Timoth Eyesbright, a heroic centaur, and Vajra Valmeyjar, a renowned warrior woman, had a protracted arm-wrestling contest in the Selûne's Smile tavern. The cosmic alignment amplified the power of their contest, which merged with magic that had sweltered in the heat and tore a mystic nexus point into a rift. This opened a door to an extra-dimensional prison, releasing Aviss and Fellandar to wreak a path of destruction in the city. Khelben Arunsun urged Vajra and Timoth to continue arm-wrestling to hold the door open, before he hurled the villains back in. Vajra and Timoth broke off, closing the rift.

A new constellation, the Lady of Mystery, was identified after the Time of Troubles in 1358 DR, following the ascension of Midnight as the new goddess Mystra, the Lady of Mysteries. The stars composing that constellation were formerly considered to be two separate constellations, the Dragon of Dawn and the Firbolg.

Faerûnian Constellations

 * The Centaur, viewable over the Sword Coast North in summer.
 * The Woman Warrior, viewable over the Sword Coast North in summer.
 * Amaunator's belt, viewable over the Spine of the World in summer.
 * Correlian, viewable in autumn.
 * Mystra's Star Circle (also known as the Crown of the North or the Cold Crown), viewable in the North in winter and autumn.
 * The Harp.
 * The Sword and Dagger.
 * The Lady of Mystery.
 * The Dragon of Dawn.
 * The Firbolg.
 * The Eyes of the Watching Woman (also known as the Double Daggers, Two Jambiyas, or the Eyes of Elah), which indicated true west in the North.
 * The Arrows of the Gods (also known as At'ar's Arrows, the Sun's Signpost, or the Caltrop), which indicated true east in the North.
 * Auroth the Ice Snake (also known as Urwath the Sand Snake by the Bedine)
 * Jassa's Dagger
 * Lavarandar's Lantern
 * The Sleepless Knights

Zakharan constellations
In Zakhara, twelve constellations named after Enlightened deities were recognized, each of which was visible in its completeness for three months of the year:
 * Hajama, visible in the Zakharan night sky in winter;
 * Hakiyah, winter/spring;
 * Haku, spring;
 * Jauhar, spring;
 * Jisan, spring/summer;
 * Kor, summer;
 * Najm, summer;
 * Selan, summer/autumn;
 * Zann, autumn;
 * Bala, autumn; and
 * Vataqatal, autumn/winter.